April 26, 2023


In the mix...literally.

There is something about the materials that we place on the bottom of our aquariums, collectively known as "substrates"- which has always appealed to me.

I find them compelling and fascinating in both form and function. 

And it's not like I see substrates as just a package of sand or gravel. It's about a combination of materials, used to create what I like to call "functionally aesthetic" effects. Yeah, I've always looked substrate materials the way other people look at cocktails:

It's about mixing stuff.

Yeah, seriously. 

Substrates in Nature are not always just uniformly comprised of one material. Rather, they're aggregations of various materials, ranging from geological materials (rocks, sand, etc.) to botanical materials, like leaves, roots, etc., and sediments (clays, etc.).

Now, in Nature, there are numerous factors which contribute to the composition of aquatic substrates , including geology, the flow velocities of the body of water, the surrounding topography, the seasonal variations in water level (ie; inundation/dessication cycles), and accumulation of materials from the surrounding terrestrial environment.

There's a whole scientific field of study about this stuff.

So, why the hell do we as hobbyists, who want to create" the most realistic approximations of wild habitats possible", always seem to just "mail it in" when it comes to substrate? I mean, for a lot of hobbyists, it's just "open a bag of _____________ sand or whatever, and call it a day" and move on to the more "exciting" parts of our tank?

I think we just rely on the commercially available stuff- and that's that.

Kind of sad. Kind of...short-sided, really.

Now, in defense of the manufacturers of sands and gravels for aquarium use- I love what they do, and what they have available. These items are of generally excellent quality, provide a wide range of choices for a variety of applications, and are readily available. Most are fantastic.

Yet, they're not the "end-all/do-all" solution, IMHO.

We can, and should go further.

Most commercially available aquarium substrates are a great "starting point" for creating more dynamic ecosystems for our aquariums. Kind of like tomato puree is to pasta sauce...a beginning! Sure, you can use just the puree and enjoy your "sauce", but isn't it always better to add a bit of this and that and build on the "base"to create something better?

It is.

And we can.


And another thing:

I have concluded- after a lifetime in the aquarium hobby, and decades of researching and visiting natural aquatic habitats of all types-that the substrate in most wild ecosystems is...well- kind of "dirty." 

"DIrty" isn't what you think, however.

It's not "dirty" in the "polluted" sense...

"Dirty" in the sense of it not being sterile or pristine the way we like to keep our substrates in aquariums.

Think about it:

Over the past century or so of the aquarium hobby, it's become pretty much "doctrine" that we don't allow stuff like uneaten food, fish waste, or "detritus" to accumulate in the substrate. We're implored to regularly siphon this stuff out of our substrate and discourage its accumulation at all costs.

Now, on the surface, I totally get this. Some of it is "Aquarium Hobby 101" kind of stuff.

Allowing uneaten food and excessive amounts of fish waste to accumulate in your sand bed is conceivably a recipe to create a "nutrient sink" which will begin degrading the water quality of your aquarium. So, we remove it...Sound advice, sure.

I mean, no one wants to have increasing phosphate, nitrate, and other organic compounds accumulating in their tank, right?

I've seen many recommendations in aquarium content over the years to siphon out your substrate weekly or monthly. Now, again, I don't have a problem in us preaching good habits to new aquarists: Don't overstock. Don't overfeed. Filter your aquarium properly. Complete regular water exchanges. I mean, sure, these are foundational "best practices", and part of the fundamentals of keeping fishes in a closed aquatic systems for the widest variety of hobbyists.

That being said, if you're NOT overfeeding, NOT overstocking, and conducting regular water exchanges in your aquarium, why is there a necessity to thoroughly siphon the substrate frequently?

Think about it for a second before you go and pelt me with stones for my heretical questioning of this "fundamental" practice in aquarium keeping. The reality is that we have been urged to siphon out "stuff" from the substrate for fear of it accumulating and degrading water quality, right?

Okay, sounds good. However, consider that, in an otherwise well-managed aquarium, the organics in the substrate are...food...for bacteria and other organisms which live within it.  

Ask yourself why we try to seek a balance of life forms within our aquairum.

And, we embrace good husbandry because we want to facilitate the proper biological function within the system. And that means, "partnering" with our friends, the bacteria- to facilitate nutrient processing. Not trying to wipe them out on a continuous basis!

So, if you're a typical aquarist, and run a properly stocked aquarium, and embrace generally accepted husbandry practices, it seems to me that aggressively siphoning the substrate is essentially removing food resources from the bacteria and other organisms which live within the substrate.  The very organisms which we rely upon to keep our little ecosystems thriving!

So, it's actually counterproductive.

Yeah- in our effort to keep the tank "clean", we are actually starving these organisms, and creating a sort of "dependency" on our aggressive, artificially imposed maintenance practices.

Much of the organic detritus we fear is an essential "component" of the substrtae- in both Nature, and in a natural aquarium system...

Okay- back to Nature for now:

When we started Tannin, my fascination with the varied substrate materials of tropical ecosystems got me thinking about ways to more accurately replicate those found in flooded forests, streams, and diverse habitats like peat swamps, estuaries, creeks, even puddles- and other bodies of water, which tend to be influenced as much by the surrounding flora (mainly forests and jungles) as they are by geology.

It's turned into a minor obsession, and I've learned a lot along the way.

Many substrates in tropical regions which are subject to seasonal flooding are comprised of a unique class of soil, the"Podzols" -soils characterized by a whitish-grey subsurface, bleached by organic acids. They have an overlying dark accumulation of brown or black illuviated humus. These soils support the rainforests surrounding blackwater streams, yet are the most infertile soils in Amazonia. 


And of course, my obsession with botanical materials to influence and enrich the aquarium habitat caused me to look at the use of certain materials for what I call "substrate enrichment" - adding materials reminiscent of those found in the wild to augment the more "traditional" sands and other substrates used in aquariums. 

And in some instances, to replace them entirely.  

Now, in many of the tropical regions we admire, the basic substrate is often referred to by ecologists simply as "fine, white sand" in most scientific papers- typically, but not necessarily a silica of some sort. And of course, other locations have slightly larger grain sizes of other pulverized stones and such. Still others are comprised of sediments which wash down from higher elevations during seasonal rains.

Deep rivers will typically have different substrate compositions than say, marginal streams or floodplain lakes, or even flooded forests. In the Amazon region, a huge percentage of the sediment and materials which comprise the substrates are from the Andes mountains, where they are transported down into the lower elevations by water flow.

This has huge foundational impact on the chemistry of the waters in the region. This process builds the fertile floodplain soils along Andean tributaries and the main stem of The Amazon.

As I mentioned before, there is a whole science around aquatic substrates and their morphology, formation, and accumulation- I don't pretend to know an iota about it other than skimming Marine biology/hydrology books and papers from time to time.

However, merely exploring the information available in scientific literature about  the tropical aquatic habitats we love so much- even just looking long and hard at some good underwater pics of them- can give us some good ideas!

The first recorded observations of bed material of the Amazon River were made in 1843 by Lt William Lewis Herndon of the US Navy, when he travelled the river from its headwaters to its mouth, sounding its depths, and noting the nature  of particles caught in a heavy grease smeared to the bottom of his sounding weight.

He reported the bed material of the river to be, "mostly sand and fine gravel." Oltman and Ames took samples at a few locations in 1963 and 1964, and reported the bed material at Óbidos, Brazil, to be fine sands, with median diameters ranging from 0.15 to 0.25 mm.

That's pretty much what we expect, right? Of course, there is more..and there are factors which impact both the composition and appearance of substrate.

First off, in some areas- particularly streams which run through rain forests and such, the substrates are often simply a soil of some sort. A finer, darker-colored sediment or soil is not uncommon. It's based on the ionic, mineral, and physical concentrations of materials that are dissolved into the water. And it varies based on water velocities and other factors, as touched on above. 

Meandering lowland rivers maintain their sediment loads by continually re-suspending and depositing materials within their channels- a key point when we consider how these materials stay in the aquatic ecosystems.

Okay, I could go on and on with my amateur, highly un-scientific review of substrates in Amazonia and elsewhere, but you get the point!

There is more to the substrate materials found in Nature than just "sand." That's the biggest takeaway here! So, as hobbyists, we have more options and inspiration to to draw on to create more compelling substrates in our aquariums!

What that means to us is (taking into account the "pasta sauce analogy", of course) is that we should consider mixing other materials into our basic aquarium sands. For example, you could mix aquatic plant soils into your sand. You could experiment with materials such as clay, or other mineral/plant-based components of varying particle sizes. 

Obviously, your substrate will look a lot different than the "typical" aquarium substrate when you start mixing materials. Your overall aquarium will, too. And that's a good thing, IMHO. I played around with this a lot in my office brackish water Mangrove aquarium, where the substrate played an integral functional role in the aquarium, as well as an aesthetic one...

You'll have to accept stuff like tinted water, turbidity, and "texture" within the aquarium.

We talk a lot about a concept that we call "substrate enhancement" or "enrichment" in the context of botanicals (we tend to use the two terms interchangeably). We're not talking about "enrichment" in the same context as say, planted aquarium people, with materials put into the substrate specifically for the benefit of plants.

Rather, "enrichment" in our context refers to the addition of botanical materials for creating a more natural-appearing, natural-functioning substrate- one which provides a haven for microbial life, as well as for small crustaceans, biofilms, fungal growths, and even algae, to serve as a foraging area for our fishes and invertebrates. 

There is something oddly compelling to me about both aquariums and natural biotopes with a diverse, interesting bottom structure.

Rather than simply "the bottom of the tank", I see the substrate as this magical place which fuels all sorts of processes within our aquariums, supporting higher life forms- and that Nature tends to it in the most effective and judicious manner possible.

Substrates in Nature- and aquariums-are diverse harbors of life, ranging from fungal and biofilm mats, to algae, to epiphytic plants. Decomposing leaves, seed pods, and tree branches prepare the substrate to recruit a complex web of life which helps the fishes we're so fascinated by to flourish.

And, if you look at them objectively and carefully, they are beautiful.

I envision that the future of mainstream aquarium practice may include creating such a substrate as simply part of "what we do." Adding a mix of botanical materials, live bacterial and small organism cultures, and even some "detritus" from healthy aquatic systems may become how we establish systems.

It's not some amazing "revolution"- it's simply an evolution of practices that we've been playing with peripherally for decades in the hobby. It's a way of looking at what's already working and trying to figure out the "whys" as we go. 

Think beyond just sands...or anything resembling "conventional" aquarium substrate. Think about what goes on in the benthic (bottom) regions in the natural habitats we love, and what benefits or support the materials which aggregate there provide for the organisms within the ecosystem.

Understand that the substrate is a dynamic, extremely important part of the aquarium, too. And what we construct our substrate with, and how we manage it, is of profound importance to our fishes!

A combination of finely crushed leaves, bits of botanicals, small twigs, etc.within the sand can form the basis for a more "biologically active" and even productive substrate. As these materials break down, they are colonized by fungi and biofilms, and impart  tannins, lignin, and other sources of carbon into the water to fuel a variety of microbial growth.


And of course, larger crustaceans and even fishes will consume the organisms which live in this "matrix", as well as possibly consuming some of the detritus from the decomposing leaves themselves. This is precisely what happens in natural aquatic ecosystems.

Because of the very "operating system" of our tanks, which features decomposing leaves, botanicals, soils, roots, etc., we are able to create a remarkably rich and complex population of creatures within them.

Let's take advantage this!

This is one of the most interesting aspects of a botanical-method aquarium: We have the opportunity to create an aquatic microcosm-on many levels- which provides not only unique aesthetics- it provides some supplemental nutritional value for our fishes, and perhaps most important- nutrient processing- a self-generating population of creatures that compliment, indeed, create the biodiversity in our systems on a more-or-less continuous basis.


Most of our substrates will simply look different.

They'll have a variegated, sediment-laden, even "dusty"-looking appearance. Something very different from the fine, white sand that we typically see in aquariums. Adding mixes of materials to our substrates creates an entirely different form and function.

Yes, there is something incredibly beautiful and useful about utilizing these alternative materials in our substrates. They have created an incredible opportunity for us as hobbyists to forge new directions in the hobby. To embrace function first, and let the aesthetics unfold as a result.

And most important- to appreciate the wonders of Nature as it is- and how these systems organize themselves into beautiful, highly unique aquariums if we let them...


This is a huge point; something which everyone who works with botanical method aquariums comes to know and usually accept. We need to have an attitude which doesn't allow us to panic; to make fast, short-term moves in favor of longer-term outcomes. It's a very different philosophy. You need to accept different aesthetics. You need flexibility. You may even have to accept short-term losses for a greater long-term good.

You need to have faith in Nature.

It's a dance. An art form. A process, and an evolution. Sometimes seemingly chaotic, other times maddeningly slow. Always alluring. Always deferring to Nature...

And it's all held together by you- the aquarist, applying as much emotion as you do procedure- all done in the proper time...at the right cadence.

Observe. Study. Learn. Share...Evolve...

...and Stay Wet.


Scott Fellman

Tannin Aquatics 


April 19, 2023

1 comment

Shattering a botanical myth: An idea that I can't "leaf alone..."

As more and more of us expand into the botanical method aquarium world, it's only proper that more and more of us experiment with different things. Being both a hobby-level "power user" and a vendor of botanicals, I certainly consider myself fairly well-versed on a lot of this stuff (okay, as "well-versed" as one can be about adding "twigs and nuts" to his aquarium!).

And, like you, I enjoy a good experiment or two, particularly when it comes to trying new botanical items for use in our aquariums!

I am often approached by hobbyists who found "such and such" a tree or bush in their yard, or while on vacation in Florida, or wherever, or from some other online vendor, and ask me if the seed pods, roots, or leaves are suitable for use in aquariums. And honestly, most of the time, I give the same answer if I have not used the item in question:

"I don't know."

Well, shit. That kind of...sucks.

"I thought that you were some kind of expert, Scott! WTF?"

I get it.

Hardly befitting of an answer from a guy who makes his living selling botanical items for use in aquariums, I know- but it's the truth. There are around 400,000 described plant species in the world, and an average of 2,000 new species are described each year!

I'm a fish geek, not a botanist, so understanding physical/chemical/environmental impact of almost any plant is "beyond my pay grade", as they say! I can only speak in general terms, or based on my own experience with specific materials. To assert otherwise would simply be irresponsible.

Yet, I think it's time to shatter a rather monolithic "myth" of sorts that we have collectively created in our hobby sector:

"Only certain tropical leaves and botanical materials are useful in the botanical-method aquarium."


The longer that I play with botanical stuff (almost three decades now)- the more I'm starting to think that you can use just about any dried leaf you can collect in your aquariums. Of course, the "qualifier" is that the leaves should be naturally fallen and dried, having expended the sugars and other chemicals within their tissues which could contribute to water quality degradation. And it's a given that you don't want leaves from areas of known agricultural pesticide use or industrial pollution in your tank.

Oh, and of course, using leaves from plants known to be toxic to higher life forms is simply a "red line" that you just wouldn't want to cross...I mean, use some common sense here! If a plant is called "Poison___________" or "Deadly Nightshade", or something equally evil-sounding, you'd have to be a complete moron to try to use it in your aquarium! (No mincing words here)


(Poison Oak. NOT a good one for aquarium use!)

Why am I getting increasingly comfortable with this position about using all sorts of leaves? Well, for one thing, it's based on my experience and the collective experience of our global community with using leaves in aquariums. Leaves seem to "function" the same in aquariums regardless of what tree they come from. Sure, some are more durable, are different structurally or aesthetically- but they all sort of do the same thing for the tree they come from, right?

Also, so many leaves of so many varieties of plants fall into waterways all over the world that it seems unlikely that you can ONLY use Catappa, Guava, Jackfruit, etc. in aquariums. Most of those aren't even found around waterways. Rather, it's stuff like species of  Ficus, etc. that you find in the bottoms of streams and rivers in the tropics. 

( Yeah, the pervasive Ficus!)

Sure, some leaves likely have greater concentrations of tannins and other beneficial compounds than others, but I dare say that many leaves are similarly comprised, thus making them acceptable for what we do.

I mean, live oak leaves from Texas or California are just as useful and beneficial in real-world aquarium applications as Jackfruit leaves from India. They just are.

Leaves don't have to be from some exotic locale to be useful for our tropical aquariums!

"Woah! Fellman just killed the market for tropical leaves after 9 years!"

Nope, of course I didn't.

I merely said that you don't HAVE to use "X" leaves from Southeast Asia to have a successful botanical method aquarium! The past decade was fun for  experimentation with exotic leaves and botanicals, but my personal conclusion is that you don't need to buy everything from us or any vendor in order to have a successful botanical method aquarium. 


You can create amazing botanical method aquariums with what you can find locally. I'm proud of the fact that I've been saying this for years- but now it's time to really scream it out loud!

When I started Tannin, I had a good working knowledge of playing with many of these items in closed aquatic environments. Catappa (Indian Almond) leaves, for example, had been used for decades by fish people to impart tannins and other substances into the water, as had guava, jackfruit, and a few other tropical leaves.

Now, it just so happens that Catappa has been studied pretty extensively by science, and it's generally acknowledged that there are some beneficial substances contained in the leaves and bark, many of which are known generally to have potentially medicinal properties.

Now, keep in mind that these substances are present to protect the tree from fungi, bacteria, and parasites, so it's likely a bit of a leap when aquarists immediately extoll the virtues of them as "fish remedies." However, flavonoids, such as Quercetin and Kaempferol, which are apparently abundant in Catappa leaves, are known to have anti-inflammatory and possibly even anti-cancer affects, and anecdotally have been determined to be beneficial to fishes.

I actually did come across a laboratory study from the Fisheries Ministry in Malaysia that determined catappa extract to be useful as a remedy and/or prophylactic for some fish diseases, so that vindicated some of the "anecdotal" stuff, in my mind.

Yet, you see tons of vaguely-worded "articles" on the purported "medicinal" properties of Catappa, typically on websites that, well- sell the leaves. And often, they're "muddy" and filled with wonderful marketing hyperbole and claims about their "powers"-all of which serve to simply compound the myths that are unfortunately so abundant in the aquarium world about botanical materials.

And I can't help but wonder- are there other, not-so-"exotic" leaves out there around the world that have similar properties? I'll be that there are- it's just that no one has really gotten around to testing them!

Could it be that the main reason that these seemingly exotic leaves from Southeast Asia and other places have been used for decades in aquarium work is because they were simply the most abundant leaves available to adventurous and resourceful hobbyists who resided in those locales?

I think so.

I mean, if these adventurous souls resided in Cleveland instead of Bangok or Malaysia, would Ash, Oak, Beech, or whatever leaves are abundant in the local forests be THE leaves we use in aquariums?

The mind wanders...

Does every dried leaf from every tree in Nature have some degree of these, or other "medicinal" compounds?

I don't know for sure. I think so, but I can't really say with certainty. I honestly don't know who does. It'd be pure speculation to make this leap, right?

We steer clear of this kind of vagueness, and rather, choose to focus on their use as an ecological base for beneficial microfauna, as aquascaping materials, and as a means to impart tannins and other substances from their tissues into the aquarium water, creating the visual tint and possibly impacting some of its environmental parameters.

Those things are typically not disputable, with the exception of to what extent they do this.

However, personal experience with a wide variety of botanical materials from around the world has made me question the "micro-dogma" we have in our sector that you absolutely HAVE to use certain tropical species of plant materials to get these effects.

Yes, I've spent the better part of three decades seeking out the most exotic botanical materials I could find, all over the world, and I've come to the rather generalized conclusion that you can essentially get the same effect in your aquarium with locally or domestically-sourced materials as you can with exotically-sourced tropical materials.

In the end, the differences may simply be more about form than function.

Sure, some just look more exotic. Some DO come from regions where our fishes hail. Some are perhaps more "regionally biotopically appropriate" than others...but in the end, most any botanical (with the caveats discussed above about toxins- and care for where/how they are collected) will accomplish the same damn thing in your aquarium.

What ARE we trying to accomplish with botanicals in our systems?

Well, we're trying to create a "substrate" for an underwater ecology- a place for fungal growths, bacterial biofilms, and other microorganisms to colonize and create the basis of a food web and a biological "filtration" system. We hope to take advantage of some of the tannins and other compounds bound up in the botanical materials to impact water chemistry as well.

And it doesn't take a "Pongo Pongo leaf" from Malaysia or a "Buganki Pod" from Borneo to do that!

It just doesn't. 

Some of the best and most successful botanical method aquariums I've ever created utilized decidedly "un-exotic" oak twigs and oak leaves! 

Botanists will tell you that most trees and plants have leaves, bark and seed pods which contain tannins and other substances. And of course, these can impact the environmental parameters of aquatic environments when submerged or steeped in water. To what extent, may only be determined by careful field/laboratory analysis- something most of us are simply not equipped, educated, or prepared to do.

Some materials may prove toxic to aquatic and other animal life if consumed, steeped, or otherwise utilized in the aquarium.  Fact.

I can't tell you if that cool seed pod you found on holiday in Ibiza or on your hiking trip in The Appalachians is going to "nuke" your Geophagus tank.

I can only tell you how I'd approach how to find out about it: Try to research what you can (there's this crazy cool site, g-o-o-g-l-e, and they have all sorts of information you can look up!), and...experiment...with what you consider "expendable" (gulp- I cringe even saying that...) fishes in a reasonably controlled setting.

Yeah, "experiment."

Risk. Chance. It's not for everyone, but if you want to use "any old seed pod" or leaf, you'll need to experiment for yourself to know for sure. Someone has to be first to taste the metaphorical "berries", and sometimes, they might be deadly.

As I've told you for years, every single botanical item which we offer has been tested- and fairly extensively- in our own aquariums, and in those of some of our friends- with our own precious fishes. It's the best way to know for sure, IMHO.  We didn't just wake up one day and decide to create a business because we found some cool acorns in a tree down the street. We spent years playing with this stuff.

And guess what? We've killed a few fishes- very few- along the way. It sucked. But we have killed some. And it wasn't just because the botanicals used were somehow "poisonous"...it was usually because we pushed it, in terms of numbers of stuff added, using the materials without preparing them, or just added too much too quickly. Even with "safe" stuff, as we've discussed many times here- you can push too hard too fast, and create potentially tragic outcomes for your aquariums. 

There is a technique to using botanical materials in aquariums. A process.

You have to prep them, add them slowly, and observe carefully.

We say this over and over to the point where you're probably sick of hearing it- but we'll keep saying it. No matter what you use, where you obtain it from- or what anyone- even myself- says. Every aquarium, every fish, every situation is different, and the possible outcomes are always subject to lots of variables.

Even "proven" natural materials can sometimes still  have unpredictable results. Because, ya' know- Nature. We're not entirely in control here.

It's as simple as that.

Anytime you add anything to your closed aquatic environment, "stuff" can happen. It's reality, as you know. Some fishes, like Apistos, Bettas, and some Characins, are very sensitive to even minute changes to their environment, and even with "safe" botanicals, you need to go slowly when adding them to an established aquarium.

Our "best practices" about what to use and how much to use have been developed in our community for many years now. Now, after a while, like anything else in the aquarium hobby, you sort of get a "feel" for what can and cannot work with botanicals.

You'll sort of look at a seed pod, leaf, or whatever, and have a sort of hunch, test them, and be very pleasantly surprised. Other times, you'll be shocked that the seemingly innocuous leaves you just added to your test tank have the fishes gasping at the surface. You just can't be sure until you test it yourself. 


Don't want the risk? 

Don't play with botanicals in your aquariums.

Simple as that.

That being said, if you're fortunate enough to have a nice oak tree nearby, for example, go for it- collect and test those leaves, and if they are not harmful, use them in your aquariums! Chances are, they'll be totally fine. This is the fun part of playing with botanicals! There is a lot of "DIY" potential here.

But you have to take the risk. 

(White Oak. Pic by Msact, used under CC BY-S.A. 3.0)

And remember, it's not all about getting the "coolest stuff" for your tank. It's not just about creating a cool "look"- although that is a collateral benefit which we all appreciate.

It's about learning and observing and appreciating what botanical materials can do in your aquarium, and how they can form the basis of your underwater ecology.

After my little "sabbatical" that I've taken from being active in the business of Tannin, it's just become a lot more clear to me that we (by that I mean vendors and hobbyists) are often placing too much emphasis on the acquisition of "stuff"- in our case, materials with exotic names and some sort of "cachet" within our niche, as opposed to understanding and celebrating the "craft" of what the botanical aquarium movement is all about. 

One of the most amazing things about our practice of adding leaves, twigs, seed pods, snd other botanical materials to our aquariums is that they can be almost "relied on" to perform in a fairly predictable manner in our aquariums.

The same natural processes which affect the decomposition of an Alder Cone from Europe impact the Sterculia pod from Southeast Asia, the oak twig from North America, the Jackfruit leaf from Malaysia, or the Banana Stem from Thailand. Colonization by biofilms, fungal growths, and the resulting decomposition which occurs are the same all over the planet.

And they're the exact same processes which govern what happens in our aquariums.

Think about that for just a second. 

We receive a LOT of questions from our community, asking what botanical is suitable for a tank intended to represent a specific environmental niche or geographic area. The answer isn't always as simple as "use this leaf" or whatever.

The reality is more nuanced, really.

We should understand conceptually that the way Nature functions is the same, regardless of what materials you're using to do the job. I know, I'm being redundant here...

However, it's a really important point, specifically for those of you who are just hell-bent on assuring yourself that every leaf, twig, and seed pod in your "Southeast Asian-themed aquarium" is, indeed from Southeast Asia! NEWS FLASH: It doesn't have to be.

Yeah, unless you live in the area that you're trying to represent in your tank, or are really dialed in to a good supply of whatever botanicals are native to that region, you're almost going to have to use stuff that's largely representative of what comes from there.

And that's just fine. Really.

Often, I'll come up with an idea for the aquarium representation of a unique niche habitat, and will spend a lot of time researching the ecology and, more important to me- the function of  the habitat, before embarking on my project. 

And yeah, more often than not, I'll find that the plants, wood, leaves, or whatever that I need to really nail the project in a a full-on "biotopic manner" are simply not available to me.

And guess what? That's okay. I don't "get stuck." 

I just don't get stressed-out about it.

You shouldn't, either. Contest entries be damned.

I'll bet that there are less than a handful of experts in the world who judge biotope aquarium contests who could even make positive identifications of the leaves used in many entrants' aquariums...especially after said leaves have been submerged for a while, have started to soften, and have recruited a "patina" of biofilms and fungal growths.

So don't stress out over this.

Yeah, I receive a lot of emails from fellow hobbyists who are "stuck" because they can't find leaves or seed pods from "that" exact plant...And so they dramatically change, or even abandon their projects as a result.

A real shame.

A suggestion, if I may?

Look for some sort of analog.

Now, sure, anyone can make dozens of arguments for why a serious biotope aquarium should have only stuff from the given region, but we'd be lying to ourselves if we expected everyone to comply with this dogmatic POV. Practicality has to reign sometimes. You simply can't get every single leaf or seed pod that is found in any given geographic area, for all sorts of reasons. I mean, you certainly should try if that's your thing- we do...and it's a kind of fun pastime for some of us!

However, let's keep it fun. 

And speaking of fun- please don't get swept up into the "hype machine" that's already forming around our little hobby sector in social media and elsewhere.

I don't want this hobby niche that I've helped play a small part in creating to become what the reef aquarium hobby is now- an endeavor dominated by the marketing and acquisition of over-priced, diminutively-sized, exotically-named "collector coral frags."

The thought of  a proliferation of botanical vendors trying to "one-up" each other on social media, with ever more exotically-named and higher-priced items (which, in reality, are often the same stuff everyone else offers, or offer little advantage to what's already available, other than they're "new" and from some other exotic locale!) frightens me.

The "'gramification" of our sector has begun in earnest. 

It makes me want to vomit.

I sold my interest in my coral business a decade ago after coming to that very realization about that hobby sector. I didn't want to be involved in the dismantling of the enjoyment of the reef aquarium hobby. I don't want that to happen with the botanical movement.

The aquarium hobby is expensive, but I don't think that our little sector needs to be. Creating "cachet" around certain natural materials is kind of weird, isn't it? And yeah, I think that I am partially to blame for that, and I'm gonna put a stop to my participation in making it that way.

I absolutely hate it when I get an email from a potential customer talking about their planned botanical-method aquarium that starts with something like, "...and when I save up enough to order some ________ pods from you, I'll start this tank!"

Shit. That sucks.

Sure, stuff costs money, but the cost of the botanicals themselves shouldn't be the primary barrier to entry for starting your next botanical method aquarium. I'm not going to contribute to the creation of said barrier. Yes, stuff costs money, but the value is what we perceive it to be. 

The reality is, we collectively have to place a greater emphasis on technique and processSharing our successes and our failures. So that we can all learn from them

And, on a personal note...a "mea culpa" of sorts:

I've struggled mentally with this tension between hobby and business of late...and I've done a terrible job at managing it. In addition to taking on a distracting side project, I stepped away a bit for my own health, leaving many of you wondering WTF was up. I handled this extremely poorly. I'm very sorry for this, and I'll make it right for all of you. Please be patient if you can.

As Tannin re-emerges from its "hibernation" (Much more on this in a later installments of "The Tint"), I'm going to double down on what got us all here: The sharing of ideas, discoveries, processes, and techniques. Building a community of adventurous, bold, like-minded hobbyists. Not simply trying to bring in more "stuff" to sell and create a "high-end" market for.

I don't intend, need, or want to do that. I never did, but I saw that it was heading in that direction, to be honest. Tannin got big- a little too big for what I intended, really. I didn't like it. Something had to give. I had to "break" or it would break me mentally. 

Change is coming.

Now, this doesn't mean we'll quit offering botanicals, or new stuff. It doesn't mean that I'm against selling stuff or making money or growing the company in a positive way.

It simply means that we're going to place emphasis on what's really needed right now: Sharing the ideas behind this stuff. More of that. Offering materials that will help you get there, without continuously trying to "one up" ourself or other vendors, by seeking to offer every type of botanical material available. Been there, done that. Let them have that headache!

We'll be offering some "staple" items of our craft; stuff that we love to use ourselves- and try to keep pricing reasonable, while still reflecting the operating costs associated with what we do.Yeah, when I stumble across something interesting, I'll make it available as I can source it.

I want to continue to make Tannin the "clearinghouse" for information on the botanical-method aquarium, rather than the source for buying everything.  A much more "personal" business. I want to have fun again. I want YOU to have fun, while being able to afford to do more. A "win-win."

We'll talk more about collecting your own stuff, using what you've got already- and directing you to alternative sources to find some of the materials that we can utilize in our botanical method aquariums. 

We will continue to offer and develop our "NatureBase" substrate line, since so many of you really have enjoyed the product, and since I love playing with and developing them! And we'll talk more about how substrate materials work in the botanical method aquarium. And yeah, I'll even share a few "recipes" for making your own similar substrates!

And sure, because I just can't help myself, I'll still try to develop some more "ecology-based" products, to help foster the microbiome that's so important to our work.

In the end, it'll be all about sharing the craft- the love- that we have for this crazy cool aquarium hobby sector.

It's been an 8 year ride. A lot has happened. A lot is yet to unfold. And the most exciting thing is that it feels like I'm just getting started again!

Thank you for your faith in me, in Tannin, and in the ideas we discuss here. Thanks for your interest, your passion, your patience- and your faith in the processes of Nature.

Let's continue to move forward together in a positive way.

Now, the future starts.

Stay bold. Stay dedicated. Stay curious. Stay diligent. Stay passionate...

And always Stay Wet.


Scott Fellman

Tannin Aquatics 


March 15, 2023

1 comment

The outer limits?


We've been playing with the "botanical method" of natural aquariums for a long time now, and during that time, we've pushed out some unconventional ideas, haven't we? I mean, the idea of embracing fungal growths, bacterial biofilms, and detritus isn't exactly popular in the mainstream hobby, right?

And there are numerous other life forms which are found on these materials as well, which we never really consider, yet are found in abundance in nature and perform vital roles in the function of the aquatic habitat.

Perhaps most fascinating  and rarely discussed in the hobby, are the unique freshwater sponges, from the genus Spongilla. These interesting life forms attach themselves to rocks and logs and filter the water for various small aquatic organisms, like bacteria, protozoa, and other minute aquatic life forms.  

(A BIG freshwater sponge! Image by Jomegat, used under CC BY-S.A. 3.0)

Unlike the better-known marine sponges, freshwater sponges are subjected to the more variable environment of rivers and streams, and have adapted a strategy of survival. When conditions deteriorate, the organisms create "buds", known as  "gemmules", which are an asexually reproduced mass of cells capable of developing into a new sponge! The Gemmules remain dormant until environmental conditions permit them to develop once again!

To my knowledge, these organisms have never been intentionally collected for aquariums, and I suspect they are a little tricky to transport (despite their adaptability), just ike their marine cousins are. One species, Metania reticulata, is extremely common in the Brazilian Amazon. They are found on rocks, submerged branches, and even tree trunks when these areas are submerged, and remain in a dormant phase in the aforementioned gemmules during periods of desiccation!

Now, I"m not suggesting that we go and collect sponges for aquarium use, but I am curious if they occur as "hitchhikers" on driftwood, rocks or other materials which end up in our aquariums. When you think about how important sponges are as natural "filters", one can only wonder how they might perform this beneficial role in the aquarium as well! Have any of you encountered one before in your tanks?

Think about the possibilities which are out there, under every leaf. Every sunken branch. Every rock.

It was suggested (years ago) in the reef aquarium hobby that sponges can be encouraged to multiply in a collection of "live rock" rubble in the sump of a reef tank. In this way, they'd be utilized as a "cryptic zone" filter...I've always loved this idea, first proferred by reef hobby pioneer, Steve Tyree...And, I think that there is a definite application for them in freshwater, too.

Of course, since there ARE currently no sponges deliberately imported for aquarium hobbyists to work with, perhaps there are other alternatives?

What about our friends- the fungi and biofilms?

And a bonus, bigger thought- one which we've discussed before; but one which bares repeating:

The aquarium-or, more specifically- the botanical materials which comprise the botanical-method aquarium "infrastructure"- acts as a biological "filter system."

In other words, the botanical materials present in our systems provide enormous surface area upon which beneficial bacterial biofilms and fungal growths can colonize. These life forms utilize the organic compounds present in the water as a nutritional source.

Oh, the part about the biofilms and fungal growths sounds familiar, doesn't it?

Let's talk about our buddies, the biofilms, just a bit more. One more time. Because nothing seems as contrary to many hobbyists than to sing the praises of these gooey-looking strands of bacterial goodness!

Structurally, biofilms are surprisingly strong structures, which offer their colonial members "on-board" nutritional sources, exchange of metabolites, protection, and cellular communication. They form extremely rapidly on just about any hard surface that is submerged in water.

When I see aquarium work in which biofilms are considered a "nuisance", and suggestions that it can be eliminated by "reducing nutrients" in the aquarium, I usually cringe. Mainly, because no matter what you do, biofilms are ubiquitous, and always present in our aquariums. We may not see the famous long, stringy "snot" of our nightmares, but the reality is that they're present in our tanks regardless.

The other reality is that biofilms are something that we as aquarists typically fear because of the way they look. In and of themselves, biofilms are not harmful to our fishes. They function not only as a means to sequester and process nutrients ( a "filter" of sorts?), they also represent a beneficial food source for fishes. They readily colonize leaves and other botanicals.

Now, look, I can imagine a few rare scenarios where massive amounts of biofilms (relative to the water volume of the aquarium) could consume significant quantities of oxygen and be problematic for the fishes which reside in your tank. These explosions in biofilm growth are usually the result of adding too much botanical material too quickly to the aquarium. They're excaserbated by insufficient oxygenation/circulation within the aquarium.

These are very unusual circumstances, resulting from a combination of missteps by the aquarist.

Typically, however, biofilms are far more beneficial that they are reven emotely detrimental to our aquariums.

Nutrients in the water column, even when in low concentrations, are delivered to the biofilm through the complex system of water channels, where they are adsorbed into the biofilm matrix, where they become available to the individual cells.  Some biologists feel that this efficient method of gathering energy might be a major evolutionary advantage for biofilms which live in particularly in turbulent ecosystems, like streams, (or aquariums, right?) with significant flow, where nutrient concentrations are typically lower and quite widely dispersed.

Biofilms have been used successfully in water/wastewater treatment for well over 100 years! In such filtration systems the filter medium (typically, sand) offers a tremendous amount of surface area for the microbes to attach to, and to feed upon the organic material in the water being treated. The formation of biofilms upon the "media" consume the undesirable organics in the water, effectively "filtering" it!

Biofilm acts as an adsorbent layer, in which organic materials and other nutrients are concentrated from the water column. As you might suspect, higher nutrient concentrations tend to produce biofilms that are thicker and denser than those grown in low nutrient concentrations.

Those biofilms which grow in higher flow environments, like streams, rivers, or areas exposed to wave action, tend to be denser in their morphology. These biofilms tend to form long, stringy filaments or "streamers",which point in the direction of the flow. These biofilms are characterized by characteristic known as  "viscoelasticity."This means that they are flexible, and stretch out significantly in higher flow rate environments, and contract once again when the velocity of the flow is reduced.

Okay, that's probably way more than you want to know about the physiology of biofilms! Regardless, it's important for us as botanical-style aquarists to have at least a rudimentary understanding of these often misunderstood, incredibly useful, and entirely under-appreciated life forms.

And the whole idea of facilitating a microbiome in our aquariums is predicated upon supplying a quantity of botanical materials- specifically, leaf litter, for the beneficial organisms to colonize and begin the decomposition process. An interesting study I found by Mehering, et. al (2014) on the nutrient sequestration caused by leaf litter yielded this interesting little passage:

"During leaf litter decomposition, microbial biomass and accumulated inorganic materials immobilize and retain nutrients, and therefore, both biotic and abiotic drivers may influence detrital nutrient content."

The study determined that leaves such as oak "immobilized" nitrogen. Generally thinking, it is thought that leaf litter acts as a "sink" for nutrients over time in aquatic ecosystems.

Oh, and one more thing about leaves and their resulting detritus in tropical streams: Ecologists strongly believe that microbial colonized detritus is a more palatable and nutritious food source for detritivores than uncolonized dead leaves. The microbial growth which occurs on the leaves and their resulting detritus increases the nutritional quality of leaf detritus, because the microbial biomass on the leaves is more digestible than the leaves themselves (because of lignin, etc.).

Okay, great. I've just talked about decomposing leaves and stuff for like the 11,000th time in "The Tint"; so...where does this leave us, in terms of how we want to run our aquariums?

Let's summarize:

1) Add a significant amount of leaf litter, twigs, and botanicals to your aquarium as part of the substrate.

2) Allow biofilms and fungal growths to proliferate.

3) Feed your fishes well. It's actually "feeding the aquarium!"

4) Don't go crazy siphoning out every bit of detritus.

Let's look at each of these points in a bit more detail.

First, make liberal use of leaf litter in your aquarium. I'd build up a layer anywhere from 1"-4" of leaves. Yeah, I know- that's a lot of leaves. Initially, you'll have a big old layer of leaves, recruiting biofilms and fungal growths on their surfaces. Ultimately, it will decompose, creating a sort of "mulch" on the bottom of your aquarium, rich in detritus, providing an excellent place for your fishes to forage among. 

Allow a fair amount of indirect circulation over the top of your leaf litter bed. This will ensure oxygenation, and allow the organisms within the litter bed to receive an influx of water (and thus, the dissolved organics they utilize). Sure, some of the leaves might blow around from time to time- just like what happens in Nature. It's no big deal- really!

The idea of allowing biofilms and fungal growths to colonize your leaves and botanicals, and to proliferate upon them simply needs to be accepted as fundamental to botanical-style aquarium keeping. These organisms, which comprise the biome of our aquariums, are the most important "components" of the ecosystems which our aquariums are.

When you think about it objectively, they're among the most important and useful organisms which we can have in our botanical method aquariums. Think about how they arrive in aquatic ecosystems, what they consume, how they derive nutrition, and what they do for the overall ecosystem.

Fungi are regarded by biologists to be the dominant organisms associated with decaying leaves in streams, so this gives you some idea as to why we see them in our aquariums, right?

In aquarium work, we see fungal colonization on wood and leaves all the time. Most hobbyists will look on in sheer horror if they saw the same extensive amount of fungal growth on their carefully selected, artistically arranged wood pieces as they would in virtually any aquatic habitat in Nature!

Yet, it's one of the most common, elegant, and beneficial processes that occurs in natural aquatic habitats!

It's everywhere.

Of course, fungal colonization of wood and botanicals is but one stage of a long process, which occurs in Nature and our aquariums. And, as hobbyists, once we see those first signs of this stuff, the majority of us tend to reach for the algae scraper or brush and remove as much of it as possible- immediately! And sure, this might provide some "aesthetic relief" for some period of time- but it comes right back...because these materials will provide a continuous source of food and colonization sites for fungal growths for some time!

I know that the idea of "circumventing" this stuff is appealing to many, but the reality is that you're actually interrupting an essential, ecologically beneficial natural process. And, as we know, Nature abhors a vacuum, and new growths will return to fill the void, thus prolonging the process.

Again, think about the role of aquatic hyphomycetes in Nature.

Fungal colonization facilitates the access to the energy trapped in deciduous leaves and other botanical materials found in tropical streams for a variety of other organisms to utilize. 

As we know by now, fungi play a huge role in the decomposition of leaves, both in the wild and in the aquarium. By utilizing special enzymes, aquatic fungi can degrade most of the molecular components in leaves, such as cellulose,, hemicelluloses, starch, pectin and even lignin.

Fungi, although admittedly not the most attractive-looking organisms, are incredibly important in Nature and useful to us as hobbyists...and they "play well" with a surprisingly large number of aquatic life forms to create substantial food webs, both in the wild and in our aquariums!

Natural habitats are absolutely filled with this stuff...It's like the whole game here- a literal explosion of life-giving materials, free for the taking...

Yet, we freak the fuck out about it when it shows up in our tanks!

It requires another "mental shift", I suppose...one which many of you have already made, no doubt.

I certainly look forward to seeing many examples of us utilizing "what we've got" to the advantage of our fishes! AGAIN- one of the most important lessons we can take away from this is:

A truly "Natural" aquarium is not sterile. It encourages the accumulation of organic materials and other nutrients- not in excess, of course.

Imagine, if you will, a sump connected to a large display aquarium, filled with leaves and other botanical materials- in which biofilms and fungal growths are encouraged to proliferate extensively. Can you imagine the level of biological support such a mechanism could provide to an aquarium?  It's essentially a freshwater, botanically-powered "refugium."


Yeah, a refugium...a concept that sort of came and went in the reef hobby, but who's time hasn't yet come in the freshwater world...

A completely unexplored (or, is it?), yet thoroughly useful way to manage nutrients and more for natural aquariums...The possibilities are endless. The potential benefits are beyond exciting. And the application really couldn't be more simple. Experimenting with a fungal/biofilm refugium would be super easy.

Stuff like this is truly at the cutting edge in our hobby- the true "outer limits" to what we know and do.

Keep pushing.

Stay progressive. Stay creative e. Stay brave. Stay engaged...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

March 14, 2023


An easy partnership

One of the more interesting aspects of what we do is the very premise behind why we do it!

A lot of people see all of the cool botanical materials that we offer and wonder what the point of it all is.. 

It's a pretty good question, right? 

I mean- think about what it is that we do here:

You take a perfectly good aquarium, fill it with water, and then proceed to toss a bunch of leaves, seed pods, bark, and twigs in it and...then what?

You let them accrue biofilms, fungal growths, and begin to decompose. Like, why?

For one thing, there are numerous life forms which are found on these materials as well, which we never really consider, yet are found in abundance in nature and perform vital roles in the function of the aquatic habitat.

Our aquariums, much like the wild habitats we strive to replicate, are constantly evolving, accumulating new materials, and creating new physical habitats for fishes to forage among. New food sources and chemical/energy inputs are important to the biological diversity and continuity of the flooded forests and streams of the tropics, and they play a similar role in our aquariums.

They are important in the nutrient cycling and uptake in both Nature and the aquarium, adding to the biodiversity, and serving as an important food source for many species of fishes.

I think that lately, there has been a very visible surge of interest in the botanical method aquarium approach, and a sort of resurgence in general in aquariums based more on Nature and less on other aquariums or fantasy-inspired aquascapes- a hugely refreshing change.

However, there is an equally annoying, and tenacious "aesthetics first" mindset which continues to hang on with many hobbyists, and yeah, with a few aquarium industry brands, even when touting "natural." It is head-scratching to me why it's so important to push the natural "look" without bothering to talk about the function.

Yes, I've been really railing on this in my last few episodes  of "The Tint", because I'm just a bit disgusted by how lazy so many hobbyists are about even attempting to learn anything beyond how two glue wood pieces together, or the latest techniques on creating "forced perspective" in their competition scapes. My little "sabbatical" has given me renewed vigor in my quest to beat the vapidity out of our hobby, one step at a time!

The concepts we talk about here constantly are just not that difficult to grasp..and quite honest, as we've done here over the years- not all that difficult to explain, really. It's just that it takes more of an investment in your time, and the deferral of immediate results to learn and talk about a concept than it does to talk about something superficial like aesthetics, or how (if you're a vendor) your product can help your tank look like a natural habitat.

Don't even get me started discussing about many aquarium hobby YouTube channels...it makes me want to vomit (or take another  "sabbatical", lol)

We as hobbyists really need to wean ourselves off of this superficially-driven, perceived "immediate gratification" mindset in favor of a longer-term, more holistic view of the aquarium as a closed ecosystem, with the aesthetics as a "collateral" of the function we foster.

It's a huge missed opportunity, IMHO. One which, if industry vendors, manufacturers, and "influencers" would take a bit more time to discuss, could result in sustainable, evolutionary changes to the hobby for extended periods of time. And yeah- likely more sales of their products!

I have long been of the opinion that a botanical-method  aquarium, complete with its decomposing leaves and seed pods, serves as a sort of "buffet" for many fishes- even those who's primary food sources are known to be things like insects and worms and such. Detritus and the organisms within it can provide an excellent supplemental food source for our fishes!

Think about Nature again:

It's well known that in many habitats, like inundated forests, etc., fishes will adjust their feeding strategies to utilize the available food sources at different times of the year, such as the "dry season", etc. And it's also known that many fish fry feed actively on bacteria and fungi in these habitats...

So, I less-than-humbly suggest one again that a botanical-method aquarium could be an excellent sort of "nursery" for many fish and shrimp species! 

You'll often hear the term "periphyton" mentioned in aquatic ecology, and I think that, for our purposes, we can essentially consider it in the same manner as we do "epiphytic matter." Periphyton is essentially a "catch all" term for a mixture of cyanobacteria, algae, various microbes, and of course- detritus, which is found attached or in extremely close proximity to various submerged surfaces. Again, fishes will graze on this stuff...constantly.

In the wild habitats, some organisms, such as nematodes and chironomids ("Bloodworms!") will dig into the leaf structures and feed on the tissues themselves, as well as the fungi and bacteria found in and among them. These organisms, in turn, become part of the diet for many fishes.

And the resulting detritus produced by the "processed" and decomposing plant matter is considered by many aquatic ecologists to be an extremely significant food source for many fishes, especially in areas such as Amazonia and Southeast Asia, where the detritus is considered an essential factor in the food webs of these habitats.


And of course, if you observe the behavior of many of your fishes in the aquarium, such as characins, cyprinids, loricarids, and others, you'll see that, in between feedings, they'll spend an awful lot of time picking at the aforementioned "stuff" on the leaves, stems, and pods within the tank. In a botanical-method aquarium, this is a pretty common occurrence, and I believe it's an extremely important "side benefit" of this type of system!

As I've discussed previously, I've maintained several botanical-based aquariums for  extended periods of time without supplementary feeding. The fishes were as fat and happy as their brethren in "well fed" aquariums.

In the wild habitats of the world, it's interesting to note that, where materials fall from the trees and surrounding dry areas, the greater the abundance of fishes and other aquatic animals which utilize them is found.

That makes sense.

Yet, the idea of embracing and even relying upon stuff like detritus, biofilms, etc.as positive influences on our tanks is at odds with what we've been taught as a hobby, isn't it?


For generations, we've been told in the aquarium hobby that we need to be concerned about the appearance of all kinds of stuff in our tanks, like algae, detritus, and "biocover".

For some strange reason, we as a hobby group seems emphasize stuff like understanding some biological processes, like the nitrogen cycle, yet we've also been told to devote a lot of resources to siphoning, polishing, and scrubbing our tanks to near sterility.

It's a strange dichotomy.

I remember when the first few botanical-method tanks I created (well over two decades ago now) hit that phase early on when biofilms  and fungal growths began to appear, and I'd hear my friends telling me, "Yeah, your tank is going to turn into a big pile of shit. Told you that you can't put that stuff in there."

Because that's what they've been told. The prevailing mindset in the hobby was that the appearance of these organisms was an indication of an "unsuitable aquarium environment"-just because it looked so different than what we've been told to be comfortable with in our tanks?

I think so.

Anyone who's studied basic ecology and biology understands that the complete opposite is true. The appearance of these valuable life forms is an indicator that your aquatic environment is ideal to foster a healthy, diverse community of aquatic organisms, including fishes!

Exactly like in Nature.

I recall reading about the guppy great, Paul Hahnel, in some of my dad's battered 1960's vintage fish books when I was growing up. He, like many of the amazing enthusiasts of the aquarium hobby's "greatest generation", adapted simple mantras about stuff like their aquariums' environments: A common refrain with guppy breeders back in the day was something to the effect that, if your Water Sprite grows well, your tank is well-suited for fish!

They were on to something there...

And in my tanks, I felt that the processes I was witnessing occurring in my tanks were beneficial, and not at all unexpected.

I remember telling myself that this is what I knew was going to happen. I studied this stuff in school. I knew how biofilms and fungal growths appear on "undefended" surfaces, and that they are essentially harmless life forms, exploiting a favorable environment. I knew that fungi appear as they help break down leaves and terrestrial botanical materials. I knew that these are perfectly natural occurrences, and that they typically are transitory and self-limiting to some extent.

Normal for this type of aquarium approach, of course.

I knew that they would go away, but I also knew that there would be a period of time when the tank might look like a big pool of slimy shit. Or, rather, it'd look like a pile of slimy shit to those who weren't familiar with these life forms, how they grow, and how the natural aquatic habitats we love so much actually function and appear!

To reassure myself, I would stare for hours at underwater photos taken in the Amazon region, showing decaying leaves, biofilms,and fungi all over the leaf litter. I'd read the studies by researchers like Henderson and Walker, detailing the dynamics of leaf litter zones and how productive and unique they were.

I'd pour over my water quality tests, confirming for myself that everything was okay. It always was. And of course I would watch my fishes for any signs of distress...

I never saw them.

Of course, I never reached for the siphon hose to remove all of this material. Never freaked out and started scrubbing the shit out of my tanks, lest any "issues" arise.

I was patient. Ever faithful in Nature. Indeed, I partnered intimately with Nature. I trusted that the processes which have played out for eons in the wild aquatic habitats of the world would unfold in my tanks, too- and that everything would be okay.

It was.

I knew that there wouldn't be any issues, because I created my aquariums with a solid embrace and appreciation of of basic aquatic biology; an understanding that an aquarium is not some sort of "underwater art installation", isolated from natural porocesses- but rather, a living, breathing microcosm of organisms which work together to create a biome..and that the appearance of the aquarium only tells a small part of the story.


I was keenly aware about how different most wild aquatic habitats are from the way we perceive them to be in our tanks.

I knew that this type of aquatic habitat could be replicated in the aquarium successfully. I realized that it would take understanding, trial and error, and acceptance that the aquariums I created would look fundamentally different than anything I had experienced before.

 A mental shift.

I also knew I might face criticism, scrutiny, and even downright condemnation from some hobby quarters for daring to do something different, and then for labeling what most found totally distasteful, or have been conditioned by "the hobby" for generations to fear, as simply "a routine part of the process."

It's what happens when you venture out into areas of the hobby which are a bit untested. Areas which embrace ideas, aesthetics, practices, and occurrences which have existed far out of the mainstream consciousness of the hobby for so long. Fears develop, naysayers emerge, and warnings are given.

Yet, all of this stuff- ALL of it- is completely normal, well understood and documented by science, and in reality, comprises the aquatic habitats which are so successful and beneficial for fishes in both Nature (and the aquarium, when we allow it).

We as a hobby have made scant little effort over the years to understand it. And once you commit yourself to studying, understanding, and embracing life on all levels, the world of natural, botanical-method aquariums and its untapped potential opens up to you.

Mental shifts are required.

Along with study, patience, time, and a willingness to look beyond hobby forums, YouTube/TikTok/Instagram, most aquarium literature, and aquascaping contests for information. A desire to roll up your sleeves, get in there, ignore the naysayers, and just DO.

No other hobby speciality is poised to study, appreciate, and embrace the vast diversity and process of Nature like we are in the aquarium world.

It's incredibly exciting- and humbling- to realize that the mental shifts that our community has taken- going beyond just the aesthetics- and really working with-indeed. "partnering" with- Nature, as opposed to fighting Her- will likely yield some of the most important breakthroughs in the history of the aquarium hobby.

An easy, beneficial partnership- wouldn't you agree?

Stay thoughtful. Stay studious. Stay diligent. Stay creative. Stay patient...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


March 09, 2023


Beyond the superficial aspects of "natural" aquariums

Okay, I'm sort of getting back into the game from a long-overdue self-imposed aquarium "sabbatical", and I'm looking at things a bit more objectively than before. Well, I was always pretty objective, but it became increasingly challenging for me to keep it that way after seeing how the hobby seems to be coalescing around aesthetics above almost all else when talking about "natural" aquarium systems. 

It's really obvious wen you step away and sort of explore social media from afar. Like, we have these ideas out there, yet the hobby in it's most popular form is embracing a really superficial approach to representing "Nature" in our tanks. 

During my "time away", I've had lots of discussions with all sorts of fellow hobbyists about how we approach the creation of our aquariums. It was enlightening to interact with people from different hobby specialities, to not only understand their POV, but to see some common threads in our philosophies and approaches.

One of the topics which kept coming up during and after conversations was thinking on a deeper level about how to more faithfully replicate the natural habitats of many of the fishes that we love so much. And Im talking about this from the function al aspect- not simply creating cool-looking tanks. Having a bit of  faith that the way Nature functions is as engaging and beautiful as the way it looks.

And of course, the the idea that there are all sorts of interesting influences on these natural habitats created by the surrounding terrestrial environment and the microbial associations which occur in the substrates, leaves, wood, and other materials which comprise them.

The relationship between terrestrial habitats and the aquatic environment is becoming increasingly apparent- particularly in areas in which "blackwater" habitats are found. And, the lack of suspended sediments, which create a "nutrient poor" condition in these aquatic habitats, doesn't do much to facilitate "in situ" production of aquatic food sources; rather, it places the emphasis on external factors.

Think about that for a second.

Many blackwater systems are simply too poor in nutrients to offer alternative food sources to fishes.The importance of the relationship between the fishes and their surrounding terrestrial habitat (i.e.; the forests which are inundated seasonally) is therefore obvious. That likely explains the significant amount of insects and other terrestrial food sources that ichthyologists find during gut content analysis of many fishes found in these habitats.

And, as we've hinted on previously- the availability of food at different times of the year in these waters also contribute to the composition of the fish community, which varies from season to season based on the relative abundance of these resources.


Another example of these unique interdependencies between land and water are when trees fall.

It’s not uncommon for a tree to fall in the rain forest, with punishing rain and saturated ground conspiring to easily knock over anything that's not firmly rooted. When these trees fall over, they often fall into small streams, or in the case of the varzea or igapo environments in The Amazon that I'm totally obsessed with, they fall and are submerged in the inundated forest floor when the waters return.

And of course, they immediately impact their (now) aquatic environment, fulfilling several functions: Providing a physical barrier or separation from currents, offering territories for fishes to spawn in, providing a substrate for algae and biofilms to multiply on, and providing places for fishes forage among, and hide in. An entire community of aquatic life forms uses the fallen tree for many purposes. And the tree trunks and parts will last for many years, fulfilling this important role in the aquatic ecosystems they now reside in each time the waters return.

Of all of the botanical materials that we employ in our aquariums, none are more common, well-studied, or simply ubiquitous in aquatic habitats than leaves.

In nature, leaf litter zones comprise one of the richest and most diverse biotopes in the tropical aquatic ecosystem, yet they are seldom replicated in the aquarium. Now, more so than in years past, but I would not call aquariums configured to replicate these habitats "common."


I think this has been due, in large part- to the lack of a real understanding about what this biotope is all about- not to mention, the understanding of the practicality of creating one in the aquarium.

It's important to understand that a leaf litter bed in Nature- or the aquarium, for that matter- is a rich ecosystem, providing food and shelter to a diverse community of organisms, ranging from fungi to bacterial biofilms.

And of course, fishes and invertebrates which live amongst and feed directly upon the fungi and decomposing leaves and botanical materials contribute to the breakdown of these materials as well! Aquatic fungi can break down the leaf matrix and make the energy available to feeding animals in these habitats.

And look at this little gem I found in my research:

"There is evidence that detritivores selectively feed on conditioned leaves, i.e. those previously colonized by fungi (Suberkropp, 1992; Graca, 1993). Fungi can alter the food quality and palatability of leaf detritus, aecting shredder growth rates. Animals that feed on a diet rich in fungi have higher growth rates and fecundity than those fed on poorly colonized leaves. Some shredders prefer to feed on leaves that are colonized by fungi, whereas others consume fungal mycelium selectively..."

"Conditioned" leaves, in this context, are those which have been previously colonized by fungi! They make the energy within the leaves and botanicals more available to higher organisms like fishes and invertebrates! 

It's easy to get scared by this stuff...and surprisingly, it's even easier to exploit it as a food source for your animals! This is a HUGE point that we can't emphasize enough.

Here is an interesting except from an academic paper on Amazonian Blackwater leaf-litter communities by biologist Peter Alan Henderson, that provides some context for those of us considering replicating these communities in our aquaria:

"..life within the litter is not a crowded, chaotic scramble for space and food. Each species occupies a sub-region defined by physical variables such as flow and oxygen content, water depth, litter depth and particle size…

...this subtle subdivision of space is the key to understanding the maintenance of diversity. While subdivision of time is also evident with, for example, gymnotids hunting by night and cichlids hunting by day, this is only possible when each species has its space within which to hide.”

In other words, leaf litter beds facilitate and accommodate diverse populations of fishes, and we should consider this when creating and stocking our botanical-style aquairum systems.

Some litter beds form in what stream ecologists call "meanders", which are stream structures that form when moving water in a stream erodes the outer banks and widens its "valley", and the inner part of the river has less energy and deposits silt- or in our instance, leaves.

There is a whole, fascinating science to river and stream structure, and with so many implications for understanding how these structures and mechanisms affect fish population, occurrence, behavior, and ecology, it's well worth studying for aquarium interpretation!  Did you get that part where I mentioned that the lower-energy parts of the water courses tend to accumulate leaves and sediments and stuff?

It's logical, right? And it's also interesting, because, as we know, fishes and their food items tend to aggregate in these areas, and embracing the "theme" of a litter/botanical bed or even wood placement, in the context of a stream structure in the aquarium is kind of cool!

Incorporating leaf litter in our aquariums opens up all sorts of possibilities for interesting experiments ranging from community displays to fry rearing systems. You can go with just a few leaves in your tank- or really go crazy with a deep bed of leaf litter in your tank. It's wide open for experimentation.

How do you create one? 

Well, it's not particularly complicated, really. Simply add a selection of the prepared leaves of your choice to your aquarium! I mean, simple... In a brand new tank, devoid of fishes, you can add as many as you want all at once. In an established, populated tank, you should build up the depth and quantity gradually  over the course of several weeks, monitoring any environmental impacts regularly, to gauge for yourself any issues which may arise along the way. Common sense, right?

How many leaves, what kind, and how often to add them is a topic open for discussion and debate, really.

I periodically ponder and discuss the idea of creating a really deep litter bed in an aquarium, to more accurately replicate some of the litter beds found in South America, Asia, Africa, and elsewhere. By "deep", I'm talking 6"- 12" (15.24cm-30.48cm). Yes, there are deeper litter beds in these areas (several feet in depth); however, for practical aquarium display purposes, I think the rational "upper limit" is likely more like the 12" (30.48cm) range.

Or, is it?

Maybe you can go as deep as you want. We simply don't really know right now. No one is really experimenting with this at the moment. As a hobby, we're too caught up in the "look", right?

Okay, back to the function thing:

In these habitats, fishes, and the other organisms present- and their processes- create not only the basis of a "food web", but the development of an entire community of co-dependant organisms, which work together to process nutrients and support life forms all along the chain.

When we encourage, rather than remove these organisms when they appear, we're helping perpetuate these processes. I can't stress how important it is to let these various organisms multiply.

And we need to re-think our relationship with leaf litter, detritus, decomposing botanical materials, and sediments in our tanks. 

Yes, I'm asking you to not only "leave them be" -but to encourage their accumulation, to foster the development and prosperity of the organisms which "work" them. 

Once again, I have to at least ask the rather long question, "Are these things (detritus; decomposing leaves) really problematic for a well-managed aquarium, optimized to take advantage of their presence  Or, do they constitute an essential component of a closed aquatic ecosystem...One which can actually provide some benefits (ie; supplemental nutrition) for the resident fishes and the community of life forms which support them?"

Oh, what a question, huh?

The beauty is that we are all able to help answer it.

Blurring the lines between nature and the aquarium, at the very least, from an aesthetic sense- and most important, from a "functional" sense, proves just how far today's hobbyists have come...how damn good you are at what you do. And how much more you can do when you turn to nature as an inspiration, and embrace it for what it is.

I'm not telling you to totally turn your back on the modern popular aquascaping scene; to disregard or dismiss the brilliant work being done by aquascapers around the world, to develop a sense of superiority or snobbery, and conclude that everyone who loves this stuff is a sheep...


Not at all.

I'm simply the guy who's passing along the gentle reminder from Nature that we have this great source of inspiration that really works! Rejoice in the fact that Nature offers an endless variety of beauty, abundance, and challenge- and that it's all there, free for us to interpret it as we like.

It's not all perfect "rule of thirds", "designer rocks", or flawless layouts and such.

Some of us just happen to like things bit more "natural" than others...

Blur the lines.

And, part and parcel in this philosophy is the practice of evolving your aquarium in ways that you may not have initially envisioned. Cutting yourself some slack...


Okay, let's say that you're kind of over your Southeast Asian Cryptocoryne biotope, and ready to head  out to South America. So, rather than tearing up the entire tank, removing all of the plants, the hardscape, the leaves and botanicals, and the substrate, you opt to remove say, only the plants and perhaps the driftwood/rocks from the tank; exchange a good quantity of the water. 

You leave the botanicals and substrate intact and move on from there...

Woooah! Crazy! You're a fucking rebel...

I know. I know. This isn't exactly earth-shattering. 

Yet, in our world of the botanical-method aquarium, the idea of leaving the substrate and leaf litter/botanical "bed" intact as you "remodel" isn't exactly a crazy one. And conceptually, it's sort of replicates what occurs in Nature, doesn't it? A bit different from the "popular" "Instagram Aquascaping" approach of, "I'm done with this tank...Let's just tear it apart and start with an empty glass box!"

Most underwater habitats emerge, accumulate, populate, evolve...and change.


Yeah, think about this for just a second...

As we almost constantly discuss, habitats like flooded forests, meadows, vernal pools, igarape, and swollen streams tend to encompass terrestrial habitats, or go through phases where they are terrestrial habitats for a good part of the year. Or, perhaps they're different types of aquatic habitats at different times of the year.

In these wild habitats, the leaves, branches, soils, and other botanical materials remain "in place", or are added to by dynamic, seasonal processes like current, weather, and cyclical leaf drop from trees. For the most part, the soil, branches, and a fair amount of the more "durable" seed pods and such remain present during both phases.

The formerly terrestrial physical environment is now transformed into an earthy, twisted, incredibly rich aquatic habitat, which fishes have evolved over eons to live in and utilize for food, protection, and complex, protected spawning areas. 

I cannot stress how insanely cool and important it is to recognize this dynamic and its impact on fishes. We've talked about this endlessly here- but each time I think about and play with the idea, my mind goes crazy with inspiration! 

It's a really big world out there. There's a lot to inspire, and lots to replicate out there.

Stay inspired. Stay passionate. Stay curious. Stay committed...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


February 22, 2023

1 comment

The beauty of adaptations...

Anyone who's kept tropical fishes for any appreciable length of time does stuff that, while maybe not intentional, doesn't exactly fit the commonly accepted "best practices" of aquarium keeping. Stuff that perhaps doesn't provide the fishes under your care with stable, comfortable environmental conditions. 

Maybe you slacked off on water exchanges for a protracted period of time. Perhaps you forgot to replace your filter media...Maybe you added a few too many fishes to that 20 gallon aquarium...What about the time you went on vacation and forgot to set up a means to feed them while you were away for 10 days? Or the time the heater failed and the water temp never got above 67 degrees F (19 C ) for like a week before you realized it?

These "lapses" are not exactly something that you want to have happen.

And yet, somehow- the fishes survived, right?

Yeah. They did.


Well, perhaps they're a lot more adaptable than we give them credit for, right?

Sure, fishes will likely always do best when provided with consistent, stable environmental conditions; conditions consistent with the environmental parameters under which they've evolved for eons.

I'm obsessed with this, as are many of you...and it's  part of what interested me in the idea of using botanical materials in aquariums in the first place...an attempt to replicate some of the physical, environmental, and chemical characteristics of the environments from which they come from in the wild.


However, it's no secret that fishes will adapt to more easily-provided "captive conditions", even reproducing under them. You only need to think about all of the captive-bred tetras which, despite evolving in soft, acidic conditions, often thrive and breed in hard, alkaline water. 

There's not really a mysterious reason why this is.

The reality is that most fishes can adjust and adapt to changing or challenging conditions if you give them a little help….The "help" is providing aquarium conditions which are chemically stable, and in the case of those measures which reflect the levels of metabolic waste in the water (nitrite, ammonia, nitrite and phosphate)- low and stable. Keep 'em well fed and stable.

It really boils down to common sense husbandry.

Stability- or, more specifically, stability within a given range of measure- is what always seems to keep fishes alive and thriving. Continuously, quickly changing, and wildly varying environmental parameters are simply stressful for fishes, and, while often not killing them quickly outright, will result in continuous stress, which can lead to disease and other medical problems over time. 

That being said, it's not imperative that every single parameter in your aquarium needs to be perfectly stable and "spot on" to hobby-grade "standards". And out concern over any variation from perfection is really unfounded, IMHO.

We get to stressed-out over minutiae, IMHO.

To get a perspective, just have a chat with some non-fish-keeping acquaintances about stuff that happens in your aquariums.

Don't you think that sometimes, as hobbyists, we tend to get a bit- well, "overly concerned" about stuff that non-hobbyists don't understand? Or, perhaps they do-more than we can even comprehend- and will occasionally come up with some "pearls of wisdom" about fishkeeping that blow us away!

Case in point:

Not too many years ago, I recall walking into my office early one morning, and I immediately was taken aback. Apparently, one of my light timers had failed, and the one of my tank lights remained on all night.

No biggie, right? Well except for the fact that it was my South American-igarape-inspired leaf litter tank, and I recently added some cool wild characins to the tank, acclimated and carefully quarantined...and then- THIS had to happen, and....you know where I'm going with this?

This was going through my mind:

"Omigod, the fishes didn't get any dark period...they've been seriously stressed..."

You will say that this wouldn't bother you- but you're totally lying! It would bother the shit out of you, too! I know that it would, 'cause you're a fish geek. It's part of what we all do.

Of course, I relayed this concern to my wife later in the day, when we touched base and asked each other how are days were progressing.

To which my wife, not at all a fish geek, yet ever the pragmatist, noted, "You know, Scott, sometimes,  unexpected things happen in the Amazon."


She was on to something there.

And it's not just lilt old me who freaks out about stuff like this. I know for a fact...

It's a fish-geek thing.

I think, that as hobbyists, we tend to get caught up in every little minute detail of the little worlds we've created for our fishes- so much so that we often forget the one underlying truth about them:

They're living creatures, which have evolved over eons to adapt to and deal with changes in their environment-big and small...or even insignificant, like an excessive amount of light one evening. 

I mean, there must have been some natural precedent for this, right? Some atmospheric phenomenon- or combination of phenomenon-which rendered the night sky inordinately bright one evening at some point in the long history of the world?

Yeah. Exactly.

Think about it for a second. 

I think this high level of concern-this "overkill", if you will, on the part of all hobbyists is based on the fact that we take great pains to assure that we've created perfect little captive environments for our fishes, and do everything we can to keep them stable and consistent.

When something out of the ordinary happens- a pump fails, a heater sticks in the "on" position, we forget to feed, etc.- we tend to get a little bit, oh...crazy, maybe?

Look, I get it: When a critical piece of environmental control equipment fails (like a heater), especially during a cold spell or heatwave, it could be life or death for your fishes. If you're about to spawn a particularly picky fish or rear some fry, it could be a serious problem. You can't really downplay those concerns. However, some of the less dramatic, non-life-threatening issues, such as a light staying on or off longer than usual one evening, a circulation pump stopping unexpectedly for a couple of hours, or forgetting to change the carbon in the filter one week, don't really create that much of a problem for your fishes when you really think about it objectively, do they?


At some time during the exisience of our fishes in the wild, there was a temporary blockage in the Igarape in which they resided, slowing down the normal flow. At some point, there might have been a once-in-a-century cold morning in the tropics, right? At some point, the swarm of Daphnia or Cadis Fly larvae that were so abundant for months at a time, weren't... 

In most instances, the animals that we keep are not so delicate, and the closed environments we provide aren't running so "close to the edge" that we should panic when some random factor changes things up one day. And consider this: When we purchase our fishes, they are unceremoniously netted out of the tank (or stream, lake, river, etc.) environment in which they reside, placed in a plastic bag, transported for who knows how long, and possibly making a few stops on the way before ultimately landing in our aquarium. 

That's a LOT of changes to cope with. Stress.

But guess what? Fishes manage to deal with it. Somehow. 

Sure, our first choice is to have rock-solid parameters and environmental conditions for our fishes 24/7/365, but sometimes stuff happens that throws a proverbial "wrench" into our plans. We have to be adaptable, flexible...just like our fishes apparently are.

So next time your light doesn't come on, or you forget to feed your fishes as you rush off to work some morning, don't stress out over it. They'll be fine. Keep calm. Always keep your concern high, but don't let obsessing over your fishes keep you from focusing on the even more important things in life (yeah, there are a few, right?).

And remember, sometimes unexpected things DO happen in the Amazon. 

There is one fundamental truth, really:

The aquarium hobby isn’t difficult.

However, it CAN be when we make it that way by imposing our own barriers and obstacles to success.  And that includes stressing out over what, in reality, are really not devastating issues for our fishes. Of course, you also have to realize that common sense is so important.

One of the unusual  inconsistencies that I’ve noticed is that, sometimes, you’ll see information about a specific fish on a  website, describing in detail it’s natural habitat.

And many natural aquatic habitats are influenced by their terrestrial surroundings.

There are all sorts of interesting influences on these natural habitats created by the surrounding terrestrial environment and the microbial associations which occur in the substrates, leaves, wood, and other materials which comprise them.

The relationship between terrestrial habitats and the aquatic environment is becoming increasingly apparent- particularly in areas in which blackwater is found. And, the lack of suspended sediments, which create a "nutrient poor" condition in these habitats, doesn't do much to facilitate "in situ" production of aquatic food sources; rather, it places the emphasis on external factors.

Many blackwater systems are simply too poor in nutrients to offer alternative food sources to fishes.The importance of the relationship between the fishes and their surrounding terrestrial habitat (i.e.; the forests which are inundated seasonally) is therefore obvious. That likely explains the significant amount of insects and other terrestrial food sources that ichthyologists find during gut content analysis of many fishes found in these habitats.

And, as we've hinted on previously- the availability of food at different times of the year in these waters also contribute to the composition of the fish community, which varies from season to season based on the relative abundance of these resources.


Another example of these unique interdependencies between land and water are when trees fall.

It’s not uncommon for a tree to fall in the rain forest, with punishing rain and saturated ground conspiring to easily knock over anything that's not firmly rooted. When these trees fall over, they often fall into small streams, or in the case of the varzea or igapo environments in The Amazon that I'm totally obsessed with, they fall and are submerged in the inundated forest floor when the waters return.

And of course, they immediately impact their (now) aquatic environment, fulfilling several functions: Providing a physical barrier or separation from currents, offering territories for fishes to spawn in, providing a substrate for algae and biofilms to multiply on, and providing places for fishes forage among, and hide in. An entire community of aquatic life forms uses the fallen tree for many purposes. And the tree trunks and parts will last for many years, fulfilling this important role in the aquatic ecosystems they now reside in each time the waters return.

In Nature, as we've discussed many times-leaf litter zones comprise one of the richest and most diverse biotopes in the tropical aquatic ecosystem, yet until recently, they have seldom been replicated in the aquarium. I think this has been due, in large part- to the lack of continuous availability of products for the hobbyist to work with, and a lack of real understanding about what this biotope is all about- not to mention, the understanding of the practicality of creating one in the aquarium.

Long-held fears and concerns, such as overwhelming our systems with biological materials, and the overall "look" of decomposing leaves and botanicals in our tanks, have understandably led to this idea being relegated to "sideshow status" for many years. It's only been recently that we've started looking at them more objectively as ecological niches worth replicating in aquariums.

 Yeah, personally- I think that the aquarium hobby has been a bit overrun, if you will, with admonitions and warnings about not doing things "the way we've done them" for so long. Concerns about "tank crashes" and "algal blooms" and stuff like that simply halted progress in looking at different, more natural ways to do stuff over the years. Look, I'm all for "best practices" and using caution and observations and such, but to stagnate because of fears of going against the grain of the hobby hegomony is, IMHO, absurd.

Sure, fishes can adapt all kinds of conditions, within reason. However, doesn't it make more sense to keep them in conditions which, on a number of levels, resemble the habitats in which they've evolved over eons?

Suree, ti does- even if those conditions may be something we've been told not to recreate in our tanks for years. I think that we've been told not to recreate these botanically rich habitats simply because the idea of decomposing materials, dark water, and fungal growths go against almost everything that we've been told to do in the hobby. 

Frustrating, I know. However, I suppose that, until more information is unlocked, the best thing that we can do is to utilize the materials that we have available in a quantity and variety which "feels right" to us, and seems to have a positive impact on our fishes.

And to take note of our findings; our discoveries.

These kinds of interesting little ideas can occupy the imagination of hobbyists for decades! And the fact is that most of what we are doing in our little botanical-infused world is simply a "best guess" in many cases...a true work in progress. Yet, a "work in progress" which may have some profound impact on the hobby for decades.



January 31, 2023


What mood you're in...and the mindset you adopt.

Every once in a while, I admit, I get a little "bored" with the hobby.

Well, not "bored", in the usual sense- but perhaps a bit annoyed with it. I have been in the aquarium hobby since I was literally a toddler, so it's understandable that now and again, it's possible to be a bit "distracted" from it, for one reason or another.

My "solution" to "resolving" the occasional hobby malaise has traditionally been to let things go on "cruise control" for a bit, or to engage in one of the many other hobby sectors. Huh? Like,  if I'm a little bit "over" South American "Igapo" simulations, I'll play around with keeping fancy Mollies. Perhaps I'm tired of characins? I'll just work on the reef tank...etc.

Sometimes- rarely, though- the best solution is to simply back away from the whole thing for a bit. Just have an aquarium or two..enjoy them from a purely superficial standpoint. To not constantly study and tweak and modify and analyze every aspect of them. A true mental break; a "re-set" to get yourself re-energized, re-focused, and reengaged. 

I did this recently, and it made a big difference in my hobby enjoyment and overall productivity.

And, the beauty of it is that you can try new stuff when you get "back in the saddle" again. I came off one of those "need to step away" cycles in mid 2019, spent a lot of time "deep diving" into some unique habitats, and suddenly had an incredible burst of creativity and a desire to try new ideas. I'd say that 2019-2021 was one of Tannin's most creative and important "eras."

The energy from this period led to the idea of the "Urban Igapo", which was my hobby homage to the seasonally inundated forests of Amazonia. Developing the techniques to actually "manage" this type of system was, to me, actually the fullest expression of the botanical-method aquarium- a literal interpretation of the function and form of these habitats, and any evolution in the Botanical Method aquarium hobby space.

Suddenly, for me, it all made sense: Recreating the way terrestrial materials interact with the aquatic environment in a very "foundational" way. Besides just managing an aquarium during wet and dry "seasons", running an "Urban Igapo" setup is a dynamic demonstration of how terrestrial materials impact, and indeed, shape, the aquatic environment.

This was a transformational thought, from a transformational time for me.

As the branches, leaves, seed pods, and soils are submerged, they recruit fungal growths, bacterial biofilms, algae, and other life forms on their surfaces- just like what happens in Nature. We need to change the nomenclature associated with "establishing" an aquarium. In the botanical method, there is no "curing" of wood- indeed, the whole hobby concept of "cycling" an aquarium simply becomes a metaphor for "function."

I think that idea of an ecology forming within the confines of the aquarium is an absolutely fundamental part of our "practice." In fact, the establishment of this ecology is the basis for everything that we do!

Like with so many things we do in the hobby, it's easy for the uninformed, or for those who haven't bothered to grasp the reasons why our tanks look and function the way they do, to focus simply on the appearance as a primary "benefit" of the botanical method aquarium. I see this a lot on social media; so-called "influencers" who attempt to set up a botanical method aquarium tend to hyper focus on the way the tank looks, and make "blanket" statements like, "The tank is so natural looking.."

Well, it IS-  but that's not the whole game. It's about how natural-functioning it is. I mean, that's the whole game. Don't participate in the "dumbing down" of our hobby speciality by focusing only on the aesthetics...please. Too many hobbyists have devoted too much energy and time into "cracking the code" of botanical-method ecology to just treat this like it's some style of aquascaping.

One of the more satisfying things about working with the botanical aquarium method "movement" is that, over the years, we've seen our thoughts evolve from fringe ideas to interesting experiments to "best practices" as more and more hobbyists began to try them for themselves.

Pretty much a given in our methodology has been to employ leaves into our aquariums. We've been talking about this for 8 years now, and although it seems like a long time, not only weren't we the first people to suggest adding leaves to aquariums. I do, however, think that we were at least among the first to suggest that leaves be added to aquariums not simply to "tint the water" or "lower the pH", but to create a functional substrate which fosters a microbiome of organisms to support the aquarium.

Yeah, it's about the ecologica function.

Long-held fears and concerns, such as overwhelming our systems with biological materials, and the overall "look" of decomposing leaves and botanicals in our tanks, have understandably led to this idea being relegated to "sideshow status" for many years. It's only been recently that we've started looking at them more objectively as ecological niches worth replicating in aquariums.

Yet, to this day, we see  a lot of social media posts by both hobbyists (and distressingly) by some aquatic vendors/manufacturers just miss the point entirely- and waste valuable "mindshare" on social media waxing on about the aesthetics of adding leaves to your tank, and how they can create a "natural look." Yes, I cringe a bit when I see this- but don't get me wrong- adding leaves to your aquarium does create a cool "look". And once again, it's pretty "natural", for sure!

However, to merely proffer adding leaves to your tank for their visual sexiness overlooks the amazing ecological benefits they provide. And, often these suggestions fail to mention the fact that, even if you want leaves in your tank just for the look- they WILL have some impact on the environment within it. And there are implications about how we manage aquariums with leaf litter present.

And, we're doing this for a reason: To create more natural-functioning aquatic displays for our fishes, which just happen to look different (and attractive!) as well. 

To understand and acknowledge  that our fishes and their very existence is influenced by the habitats in which they have evolved. 

Wild tropical aquatic habitats are influenced greatly by the surrounding terrestrial geography and flora of their region, which in turn, have considerable influence upon the population of fishes which inhabit them, and their life cycle.

The simple fact of the matter is, when we add leaves and other botanical materials to an aquarium and accept what occurs as a result-regardless of wether our intent is just to create a different aesthetic, or perhaps something more- we are to a very real extent actually replicating  the processes and influences that occur in wild aquatic habitats in Nature!

The presence of botanical materials such as leaves in these aquatic habitats is essential.


In the tropical species of trees, the leaf drop is important to the surrounding environment. The nutrients are typically bound up in the leaves, so a regular release of leaves by the trees helps replenish the minerals and nutrients which are typically depleted from eons of leaching into the surrounding forests.

Most tropical forest trees are classified as "evergreens", and don't have a specific seasonal leaf drop like the "deciduous" trees than many of us are more familiar with do...Rather, they replace their leaves gradually throughout the year as the leaves age and subsequently fall off the trees.

The implication here?

There is a more-or-less continuous "supply" of leaves falling off into the jungles and waterways in these habitats, which is why you'll see leaves at varying stages of decomposition in tropical streams. It's also why leaf litter banks may be almost "permanent" structures within some of these bodies of water!

In Nature, leaf litter zones comprise one of the richest and most diverse biotopes in the tropical aquatic ecosystem, yet they were, for years, seldom-if ever- replicated in the aquarium. I think this was due, in large part- to the lack of continuous availability of products for the hobbyist to work with, and more importantly- a real understanding about what this biotope is all about- not to mention, the understanding of the practicality of recreating one in the aquarium.

Fast-forward a few years, and many of us are playing with the idea of incorporating leaf litter into our tanks- something that was given little more than a passing bit of attention a few years ago, if that.  This increased level of attention to this environmental niche among hobbyists is reaping benefits for those who have played with it.

Leaves are sort of the "gateway drug", if you will, into our world.


And it is a different world now. 

One in which your love for the hobby can certainly be influenced by the mood that you're in, and the mindset which you adopt.

Stay curious. Stay bold. Stay engaged. Stay diligent...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 23, 2022


Oak: The "one-stop-shop!"

I'm often asked what my fave all-time botanical is for our aquariums.

Now, you'd think that I'd likely reference some exotic seed pod, leaf, or root, right? The reality is that my all-time favorite botanical to use in our botanical-method tanks is oak twigs, branches and leaves.

Yeah, the humble, decidedly "non-exotic" Oak tree is sort of a "one-stop-shop" for the botanical method aquarium enthusiast.

Why Oak?

These are some of the best materials to use because, IMHO, they not only contribute to the physical structure of your tank- they also impact the ecology and water chemistry in significant ways as well. They are all surprisingly durable, long-lasting, and aesthetically pleasing, too!

Oak twigs and branches absorb water and begin to impart tannins, lignins, and other compounds into the water. Not only will you notice a visible "tint" to the water when you utilize oak branches and twigs, you'll have a perfect "substrate" upon which biofilms and fungal growths can colonize.

The other beauty of oak is that you can collect these materials yourself, if you have a source of them nearby!

Oak belongs to the genus Quercus, of the beech family (Fagaceae), with almost 500 species. A large and diverse genus, which, according to Wikipedia "is native to the Northern Hemisphere, and includes deciduous and evergreen species extending from cool temperate to tropical latitudes in the Americas, Asia, Europe, and North Africa. North America has the largest number of oak species, with approximately 160 species in Mexico of which 109 are endemic and about 90 in the United States. The second greatest area of oak diversity is China, with approximately 100 species."

So, in plain English, Oak is found across a broad swath of the planet, making it one of the most readily available and accessible botanical resources for hobbyists worldwide. The fact that you can collect them yourself if you can source them is a huge plus! 

(Image by Jurgen Eissink -CC-by S.A. 4.0 )

Now, like any botanical, sourcing and preparation are important considerations with oak-derived materials. If you collect them yourself, or purchase them from a well-regarded vendor like, I dunno- say...Tannin Aquatics- you're going to be working with materials that are essentially clean and non-polluted. Which means that preparation is going to consist of steeping or boiling leaves, and steeping or (if you have a big enough pot or vat) boiling of twigs/branches.

Yeah, let's digress a bit...The old question about why we prepare stuff comes back yet again:

You see it on our packaging, hear it discussed on "The Tint" podcast, and read about it in articles we publish here and elsewhere. Yet, there appears to be some confusion about what exactly we mean by "preparation."

Yeah, it's not a secret that, before you throw those seed pods and leaves into your aquarium, you need to do some preparation.


And why are we talking about this again?

Well, seriously, I still receive about 3-4 emails every single week from customers of ours (and from others, apparently!) asking what to do with botanicals after  they receive them...So, it's obvious to me that some people just aren't seeing this stuff, hearing it, reading our instructional cards, social media posts, etc., or not getting advice from the people they purchased their leaves, or whatever from. (Isn't EBay great! What a resource for serious hobbyists!)




I know, it's starting to sound a bit repetitive...

However, with the world botanical-style aquariums growing at an exponential rate, and more and more hobbyists entering into the fray- many of whom are enamored by the beautiful aesthetics of these tanks, it's important-well, actually essential- to revisit this stuff again and again.

And really, because most of the new vendors into our market space simply appropriate much of the information we put out to help the community, and use it to push their products, let's at least give those lazy-ass motherf---ers something useful to share (and since they're not bothering to provide this information, themselves...)!

Okay, mini-hate-rant over. For now.

"So, you're really into boiling and steeping botanical, huh?

Yes. I am. That's my thing.

"Why do you do that?"

Consider that boiling water is used as a method of making water potable by killing microbes that may be present. Most nasty microbes essentially "check out" at temperatures greater than 60 °C (140 °F). For a high percentage of microbes, if water is maintained at 70 °C (158 °F) for ten minutes, many organisms are killed, but some are more resistant to heat and require one minute at the boiling point of water. (FYI the boiling point of water is 100 °C, or 212 °F)...But for the most part, most of the nasty bacteria that we don't want in either our tanks or our stomachs are eliminated by this simple process.

So, wouldn't it make sense to boil, or at least steep, our botanicals before we dump them into our aquariums?

Yeah, it would.

Ten minutes of boiling is "golden" to assure a "good kill", IMHO. Of course, we boil for other reasons, too-as we'll touch on in a bit.

The most important reason that we boil botanicals is to kill any possible microorganisms which might be present on them. Leaves, seed pods, etc. have been exposed to rain and dust and all sorts of things in the natural environment which, in the confines of an aquarium, could  introduce unwanted organisms and contribute to the degradation of the water quality.

And, the surfaces and textures of many botanical items, such as leaves and seed pods lend themselves to retaining dirt, soot, dust, and other atmospheric pollutants that, although quite likely harmless in the grand scheme of things, are not stuff you want to start our with in your tank!

So, we give all of our botanicals a good rinse with fresh water.

Then we boil them.

Boiling also serves to soften botanicals. This is important to do for a number of reasons...

Well, the most obvious to us is thats it helps saturate the tissues of the botanicals and make them sink. I mean, who wants a bunch of floating seed pods and leaves in their aquairum? Wait, don't tempt me here...

If you remember your high school Botany (I actually do!), leaves, for example, are surprisingly complex structures, with multiple layers designed to reject pollutants, facilitate gas exchange, drive photosynthesis, and store sugars for the benefit of the plant on which they're found. As such, it's important to get them to release some of the materials which might be bund up in the epidermis (outer layers) of the leaf.  As we get deeper into the structure of a leaf, we find the mesophyll, a layer of tissue in which much of photosynthesis takes place.



We use only dried leaves in our botanical style aquariums, because these leaves from deciduous trees, which naturally fall off the trees in seasons of inclement weather, have lost most of their chlorophyll and sugars contained within the leaf structures. This is important, because having these compounds present, as in living leaves, contributes excessively to the bioload of the aquarium when submerged...

Personally, I feel that we have enough bioload going into our tanks, so why add to it by using freshly-fallen leaves with their sugars and such still largely present, right? I mean, it's definitely something worth experimenting with in controlled circumstances, but for most of us botanical method aquarium geeks, naturally fallen, dried leaves are the way to go.

I'm still going to recommend that, like I do- that you embrace a preparation process for every botanical item that you add to your aquariums.

Now, with twigs and branches, the idea of practicality comes in. Most of us simply don't have freaking cauldron or big-ass kettle- let alone, a "stove" large enough upon which to boil a bunch of branches, right?

So, compromise is in order.

Soaking is not a bad thing.

I've touched on the idea of "in situ" preparation of wood,  and it really does make sense with oak branches (largely because of the size issue)- and consider this:

It's pretty obvious that at least part of the reason we see a burst of new algae growth and biofilm in wood recently added to an aquarium is that there is so much "stuff" bound up in it. "Organics", like sugars, lignins, and compounds found in soils, etc.  Algal and fungal spores can literally "bloom" during the initial period after submersion. It's exactly what happens in the wild aquatic habitats of the world when tree trunks and branches are covered by water.

I get it- a lot of hobbyists simply don't want to see this stuff in their display tank.

On the other hand, the adventurous aquarist in me can't help but wonder if we should just give the wood a thorough washing, and let this whole process play out in the aquarium, to foster this amazing biodiversity within the aquarium itself.

Again, this is an example of setting up an aquarium from the start to replicate both the form and function of Nature.

Why NOT do this? Especially with "self-collected" stuff like oak branches.

What would the "downsides" be? I've done this many times with no issues. However, the experience IS a bit different.

It's starts with what you see.

Yeah, you'll see a lot more biofilm, fungal growth, detritus, and perhaps even slightly hazy water. You'll have to carefully monitor the nitrogen cycle, and manage nutrient accumulations with good husbandry...

You'll have to employ a lot of patience, and yeah, I'd recommend testing during the "break-in"process. Testing for what? Well, I'd likely do ammonia and nitrite, for starters. "Have you done all of this testing when you tried this, Scott?"

Not always, I admit. Why? For one thing , it's because I'm in no rush to add fishes to brand-new tanks. Because I let my tanks develop biologically for a long time before I add them. I did out of sheer curiosity, of course! And the "cycle"time was really nothing extraordinary at all.

Really, the biggest difference between this "in-tank-curing" and using an external container was that any of the stuff that emerged from the wood itself would leach into, and "accumulate" in the display tank, and impact the water appearance, and chemistry. Although I admit, I didn't notice a significant difference in nitrate or even phosphate in new tanks where the "curing" process was undertaken internally.

Remember, I'm a water exchange fanatic; I perform 10% water exchanges in every tank I maintain- every week, without fail.  So there was some dilution of whatever organics were found in the water.

The biggest difference determined by testing was often TDS. And of course, because TDS represents the "total concentration of dissolved substances" in water it can include both inorganic salts, as well as a small amount of organic matter. To me, "TDS" is always a bit of a vague thing; I mean, it can be so many different things. Regardless, when I cured "in situ", TDS readings were higher than in tanks where this process wasn't employed.

Do some of the other materials leached out of wood have implications for the healthy break-in and operation of your aquarium?  Can you even test for everything that leaches out of newly submerged wood, other than simply labeling these compounds as "organics?"

Likely NOT, in the hobby world.

Well, lignin is one substance that you might find leaching out of wood. And there are actually lignin test kits out there for scientific work; I suppose it would be interesting and informative to test for them to see what the concentration was, although I'm not really sure what function it would perform, other than just kind of "knowing."

Just like with testing for tannins, Interpreting what is "baseline" or even "okay" for lignin is something we have never really done in the hobby, right?  Another supposition would be that lignin concentration might be different in a filtered aquarium than it would be in some big container of water without a filter that you might cure wood in.

The point is, there are some things that we just don't know. We assume. I Mean, whenever we "cure" wood externally, we almost always see lots of that yucky biofilm and fungal growth on the surface tissues. That's "par for the course" when terrestrial materials are submerged. The real issue that makes "in situ" curing a bit unusual is the possible "gross pollutants" that may leach out of the wood. I suppose that would be stuff like dust, dirt, maybe some small amounts of sap, etc., bound up in or on the surface tissues of the wood.

I did a lot of research on this in the online forums, articles, etc, and the reasons why it's recommended that wood be "cured" outside of the display tank are always listed as (in no particular order):"to leach out impurities","to leach out tannins", to "let the fungal growth subside", and "to waterlog and sink."

Now, other than "waterlog and sink" process, which you can accomplish in the display tank by simply placing a few rocks on the wood, IMHO none of the other reasons given for external curing of wood are really "non-starters" here.

It's occasionally stated that boiling wood or extended soaking helps eliminate potential parasites that might be present in/on the wood. I'd hazard a guess that most wood used in aquariums doesn't have significant populations of parasites that could harm fishes, either. And again, even if there are such parasites present, if you're taking your time to add fishes (essentially keeping your tank "fallow" for a period of time) you're essentially denying any parasites that are present their "hosts", right? 


Am I missing something here? 

I don't really think so. It's just that I don't see the "stuff" that happens during the curing process as a problem.

"In situ" curing isn't a perfect, guaranteed route to accomplishing everything you want to easily, but it works. And the process and its impacts on the ecology of your aquarium is not all that different than what occurs in Nature, when you think about it.

In Nature, it is not uncommon at all for small (and large) trees to fall in the rain forest, with punishing rain and saturated ground conspiring to easily knock over anything that's not firmly rooted!


When these trees fall over, they often fall into small streams, or in the case of the varzea or igapo environments in The Amazon ( the ones that I'm totally obsessed with), they fall and are ultimately submerged in the inundated forest floor when the waters return.

And of course, they immediately impact their (now) aquatic environment, fulfilling several functions.

Fallen trees provide a physical barrier or separation from currents, perhaps creating a little "dam", which accumulates leaves, sediments, and detritus- all important as food sources to a huge number of aquatic organisms. 

They also provide a "substrate" for algae and biofilms to multiply on, and providing places for fishes forage among, and hide in. Many fishes, like small cichlids, will reproduce and raise their fry among these fallen tree trunks.

An entire community of aquatic life forms uses the fallen tree for many purposes. And the tree trunks, branches, and other parts of the tree will last for many years, fulfilling this important role in the aquatic ecosystems they now reside in each time the waters return.

So, all of this talk of prep is important...but the idea of "prep" can encompass many things. It's one of those things that we as hobbysits know to do, but we always sort of second guess  ourselves about HOW to do it.

The fact is, we need to embrace SOME sort of preparation protocol for any natural materials that we add to our aquariums. 

Okay, that was a huge detour, but a necessary one.

I love creating tanks in which the "hardscape" consists mainly of twigs and small branches.  Oak is the perfect "provider" of these materials, BTW. It keeps things simple and easy.

The beautiful thing about this idea is that you don't necessarily have to use 12 different varieties of branches and such to create a remarkably complex and interesting scape. Just oak!

Oak twigs and branches, and oak leaves are pretty much all you need for a sweet botanical-method aquarium, IMHO.


It's not just about then aesthetic, of course.

The idea is that you're creating a matrix of these materials to impart a very natural and interesting look to the aquarium. These aggregations provide fishes with hiding places, foraging areas, and spawning sites, just like they do in Nature.

We're talking mainly about twigs and roots...nto big branches here. 

Now, such root/branch tangles DO take up some physical space in the confines of the aquarium, and you need to take this into account when stocking, equipping, and maintaining such systems. Access, water capacity, and filter intakes/outputs need to be considered when you move in a project like this...but that's half the fun, anyways- right?

At the end of the day, the use of twigs, roots, and branches, the organisms which take advantage of them is one of the most stunning aspects of Nature that we can  see in our own aquariums, provided we don't "edit" them out of our tanks.

Like any dynamic habitat, the "twig and root" microhabitat relies on a variety of organisms to do the job of processing nutrients. A diverse assemblage of organisms dwelling in this layer, ranging from bacteria to fungi, to worms and small crustaceans- comprise what we call the "infauna." Essentially, the infauna is a collective of organisms which do most of the work in keeping a botanical-method aquarium functional and healthy.

Be kind to these organisms, and they'll no doubt be kind to you, too.

And of course, this habitat is perfectly analogous to what you see in Nature, isn't it?

In Nature, we see leaves and other materials accumulate in these root tangles and aggregations of fallen branches, so recreating this in nature is kind of a "no brainer!" 

When assembled in conjunction with a nice aggregation of leaves, this configuration  provides a remarkably interesting aquarium with a different sort of aesthetic. 

Looks, function, versatility...That's what makes Oak literally a "one-stop" shop for your botanical-method aquarium needs!

Stay creative. Stay inspired. Stay engaged. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

November 02, 2022


The "detritus dilemma"- again.

"Detritus is dead particulate organic matter. It typically includes the bodies or fragments of dead organisms, as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose or remineralize the material." (Source: The Aquarium Wiki)


That doesn't sound so good, does it?

It's one of our most commonly used aquarium terms...and one which, well, quite frankly, sends shivers down the spine of many aquarium hobbyists. And judging from that definition, it sounds like something you absolutely want to avoid having in your system at all costs. I mean, "dead organisms" and "fecal material" is not everyone's idea of a good time, ya know?

Literally, shit in your tank, accumulating. Like, why would anyone want this to linger- or worse- accumulate- in your aquarium?

Yet, when you really think about it and brush off the initial "shock value", the fact is that detritus is an important part of the aquatic ecosystem, providing "fuel" for microorganisms and fungi at the base of the food chain in aquatic environments. In fact, in natural blackwater systems, the food inputs into the water are channeled by decomposers, like fungi, which act upon leaves and other organic materials in the water to break them down. 

And the leaf litter "community" of fishes, insects, fungi, and microorganisms is really important to these systems, as it assimilates terrestrial material into the blackwater aquatic system, and acts to reduce the loss of nutrients to the forest which would inevitably occur if all the material which fell into the streams was washed downstream!

That sounds all well and good and well, grandiose, but what are the implications of these processes- and the resultant detritus- for the closed aquarium system?

In years past, aquarists who favored "sterile-looking" aquaria would have been horrified to see this stuff accumulating on the bottom, or among the hardscape. Upon discovering it in our tanks, it would have takennanoseconds to lunge for the siphon hose to get this stuff out ASAP!

In our world, the reality is that we embrace this stuff for what it is: A rich, diverse, and beneficial part of our microcosm. It provides foraging, "Aquatic plant "mulch", supplemental food production, a place for fry to shelter, and is a vital, fascinating part of the natural environment. 

It is certainly a new way of thinking when we espouse not only accepting the presence of this stuff in our aquaria, but actually encouraging it and rejoicing in its presence! 


Well, not because we are thinking, "Wow, this is an excuse for maintaining a dirty-looking aquarium!" No.

We rejoice because our little closed microcosms are mimicking exactly what happens in the natural environments that we strive so hard to replicate. Granted, in a closed system, you must pay greater attention to water quality, but accepting decomposing leaves and botanicals as a dynamic part of a living closed system is embracing the very processes that we have tried to nurture for many years.

Sure, it's a very different aesthetic than what we have been indoctrinated to appreciate over the years: Brown water, leaves, stringy algae films, and bits of botanical debris. We may not want to have an entire bottom filled with this stuff...or, maybe we might!

Think about it. Much of this material is not only already broken-down or rendered "inert" by beneficial bacteria and microorganisms which live within the "matrix"- it's processed into a more easily-assimilated form for other aquatic animals. 

Check your water parameters. Are you seeing surging nitrate levels? Do you have any detectible ammonia or nitrite? Are the fishes healthy, relaxed, and active? If the answer to the first two questions is "no", and the last is "yes"- and I suspect that it will be in well-managed systems- then perhaps it's time to enjoy whats happening in your aquarium!

If you are having issues with ammonia/nitrite, you have more problems than just some detritus, IMHO. If you have some significant accumulations of nitrate, it's important to review the husbandry processes you employ. I know from personal experience in both freshwater and reef/coral propagation systems that you can have significant quantities of detritus "in play" without deteriorated water quality.

It's a balance- like everything else in our aquariums. I know that sounds a bit like a "cop out"- but it's a reality. 

To accept and understand that the aesthetic of a heavily botanical-influenced system is simply different than what we've come to perceive as "acceptable" in the general aquarium sense.

It's not for everyone.

It's not something that we are used to seeing. However, the feedback we've been getting from you- our customers- regarding the systems you've set up in this fashion is that they have created an entirely new perception and understanding of a freshwater aquarium. They've enabled us all to try a completely different aesthetic experience, to understand processes that occur naturally, which are of great benefit to the fishes we keep.

Attempting to keep our tanks essentially "sterile" is an almost futile, and ultimately detrimental practice, IMHO.  The idea of creating "unnaturally clean" conditions likely results in some microorganisms struggling to find food. Now our aquariums are not absolutely "natural", open systems. However, embracing some natural processes and emulating functions of wild ecosystems might be a key "unlock" in order for certain organisms to survive and thrive long term.

Detritus/mulm- whatever you call it- serves as a food source- and a food "processing/producing" source for fishes and the other aquatic organisms which live in our tanks. 

And yeah- detritus is found in gut content analysis of many fishes. Here is a charming passage, with a rather comprehensive description of gut contents from one of our fave fishes, the Cardinal Tetra: 

"The stomach content was categorized as “detritus”... when it was found in sufficient quantities within the proper stomach, so that the conclusion of “detritus-feeding” appeared as a realistic proposition...the hind gut, filled with the digested material, practically always contained particles that could be listed as detritus. In addition, small quantities of detritus particles remain from prey guts, and/or enter the stomach when the fish are browsing for small prey over the surface of plants, litter and woods." 

So, yeah- use common sense in stocking, feeding, and maintaining your aquarium  However, I think stressing a bit less about keeping our aquariums completely spotless is a really good step to take.

I think so. Really.

And consider this: The "detritus" that we're convincing you to embrace in your aquarium is NOT uneaten food or excesses of fish feces. It's broken-down botanical materials and their associated components. Stuff like that. The result of biological processes of decomposition and bacterial colonization/assimilation. Not the result of poor fundamental aquarium husbandry.

We should all know that uneaten food and fish poop, accumulating in a closed system can be problematic if overall husbandry issues are not attended to. We should all know that it can decompose, overwhelm the biological filtration capacity of the tank if left unchecked. And that can lead to a smelly, dirty-looking system with diminished water quality. I know that. You know that. In fact, pretty much everyone in the hobby knows that.

Yet, as a hobby, we've really sort of heaped detritus into this "catch-all" descriptor which has an overall "bad" connotation to it. Like, anything which is allowed to break down in the tank and accumulate is bad. Anything that looks like "dirt" is...well, "dirty", dangerous, and should be treated accordingly.

Now, "dirty-looking" and "dangerous" are two very different things, right? Do natural habitats look "dangerous" to the life forms which reside in them?

Now, if it's uneaten food that you're seeing accumulate in excess, then you need to figure out a more accurate feeding approach. Same with fish waste. At the very least, you likely need better circulation and mechanical filtration within your system. And of course, you need to address why it is you have so much uneaten food accumulating in your system!

In botanical-method aquariums, however, if most of what is accumulating in your mechanical filter media and on the substrate, etc. is just broken-up, decomposing bits of botanicals, I'd have little concern. That's what happens to terrestrial materials in an aquatic environment. It's normal for these types of aquariums. As we've discussed ad infinitum here, various organisms, like fungi, etc., work to break down these materials and begin the decomposition process. It's part of the natural "operating system" of the botanical-method aquarium.

Nature, however, can be a rough place. The natural aquatic world doesn't take lightly to those who seek to edit it, parse it, or circumvent it. 

It's true.

We know this, because when we try to "beat the system" by skipping a step, wishing things away, or ignoring Nature's "rules", bad outcomes usually follow.

But, here's the thing...

Even when we DO "cheat"; even when we take a "shortcut"; even when we fly in Her face- after the "ass kicking" - She's got our back...

For example, when you aggressively siphon your sand, interrupting Her process by removing the bulk of the detritus, biofilms, or other organics, not to mention the organisms which utilize them, there might be consequences like a temporary ammonia or nitrite spike.

Bad, right?

Well, yes...

However, after the spike, if you are patient, keep feeding your tank, and don't do anything stupid, like adding more fishes- your tank will recover. Beneficial bacteria and microorganisms populations will re-establish themselves.

Our aquariums are a lot more resilient than we give them credit for.

The passage of time and a "hands-off" approach to this recovery is crucial. Nature  is oddly forgiving in this regard. We simply have to give Her the opportunity to continue on, as She has for eons, without our continued interference.

As we've mentioned repeatedly, Nature "does Her thing" regardless of what we think. Algal blooms appear because the conditions favoring their growth- light and nutrient loads, favor their establishment and growth. And they'll continue to do so as long as these factors remain in play. If we back off the light and continue regular nutrient export processes, at some point, the algae bloom will fade to a more "tolerable" level. 

Now, sure- some of Nature's processes require us to make "mental shifts" to accommodate.

Detritus, like biofilms, and fungal growths- as objectionable in appearance though they may be to us as aquarists- perform vital functions in Nature and in the aquarium. They are not only normal- they're beneficial. They are something that we have been indoctrinated to loathe; to fear.

Why? Largely because they look "yucky." Because they tear at our aesthetic sensibilities. They go against everything that we've been told is "healthy"- when the reality is that the appearance of these life forms is your confirmation from Nature that everything is functioning as it should.

We can benefit enormously as aquarists by embracing Nature in its most unedited, literal form.

And that is something that we understand is not appealing to everyone. And sort of "sticking it in everyone's face" and suggesting that a truly "natural" aquarium requires the acceptance of a very polarizing aesthetic certainly can turn off some people.

I do get it. 

However, I see little downside to studying Nature as it is.

It's very important, IMHO, to at least have a cursory understanding of how these habitats have come to be; what function they perform for the piscine inhabitants who reside there, and why they look the way they do. Even if you simply despise the types of aquariums we love here!

And detritus?

Learn to understand it, appreciate it, and yeah- embrace it as a "partner" in your quest to create and maintain a healthy, natural aquatic ecosystem.

Stay patient. Stay observant. Stay bold. Stay grounded...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



October 26, 2022


Waiting for the quiet storm...

There is something truly remarkable about natural processes playing out in our own aquariums, as they have done for eons in the wild.

To a certain extent, every aquarium we work with relies on certain natural processes to occur within it. However, in many "conventional" approaches, hobbyists will make every effort to limit some of the parts of natural processes which they find to be unattractive or "excessive" (a word I hear bandied about on YouTube about "stuff" which offends some people's aesthetic sensibilities, like detritus, fungal growth, tinted water, etc.)- stuff we embrace in our world. 


Understanding, accepting, and celebrating "The Bloom"  (that explosion of fungal growths, biofilms, and the process of decomposition) is all part of that "mental shift" towards accepting and appreciating a more truly natural-looking, natural-functioning aquarium. The "price of admission", if you will- along with the tinted water, decomposing leaves, etc., the metaphorical "dues" you pay, which ultimately go hand-in-hand with the envious "ohhs and ahhs" of other hobbyists who admire your completed aquarium when they see it for the first time.

It's like a quiet little "storm" of life.

Starting a new botanical method aquarium is an exciting, fun, and interesting time.  And the process of creating your aquarium is shockingly easy, decidedly un-stressful, and extremely engaging.

The main ingredients that you need are vision, a bit of knowledge, and... patience.

Oh, and a bit of a philosophical adjustment- a "mental shift."

Bringing your tank from a clean, dry,"static display" to a living, breathing microcosm, filled with life is an amazing process. This, to me is really the most exciting part of keeping botanical method aquariums. 

And how do we usually do it?

I mean, for many hobbyists, we've been more or less indoctrinated to clean the sand, age water, add wood, arrange plants, and add fishes. And that works, of course. It's the basic "formula" we've used for over a century.

Yet, I'm surprised how we as a hobby have managed to turn what to me is one of the most inspiring, fascinating, and important parts of our aquarium hobby journey into what is more-or-less a "checklist" to be run through- an "obstacle", really- to our ultimate enjoyment of our aquarium.

When you think about it, setting the stage for life in our aquariums is the SINGLE most important thing that we do. If we utilize a different mind set, and deploy a lot more patience for the process, we start to look at it a bit differently.

We don't "lose our shit" if our water gets a little bit turbid or there is a bit of botanical detritus accumulating on the substrate. Just wait it out. What's the big rush?

And guess what? We don't have to start a tank with brand new, right-from-the-bag substrate when starting or "remodeling" our tank.

Of course not.

We can utilize some or all of the old substrate from the existing aquarium, or another, well-established tank (we have done this as a hobby for generations for the purpose of "jump starting' bacterial growth) for the purpose of providing a different aesthetic as well.

And, you can/should take it further: Use that slightly biofilm/algae-covered piece of driftwood or rock in your brand new tank, or some fungal-colonized, partially decomposed leaves from the established tank that you have...This helps rapidly foster a habitat more favorable to the continued proliferation of the microorganisms, fungi, and other creatures which comprise an important part of our closed aquarium ecosystems.

"The Bloom."

In fact, in a botanical-method aquarium, facilitating the rapid growth of such biotia is foundational.

Don't confuse "healthy" with "dirty-looking."

It's okay for your tank to look a bit "worn" right from the start.

In fact, I think most of us actually would prefer that! It's okay to embrace this. From a functional AND aesthetic standpoint. Employ good husbandry, careful observation, and common sense when starting and managing your new aquarium.

But don't obsess over "pristine." Especially in those first hours.

The aquarium still has to clear a few metaphorical "hurdles" in order to be a stable environment for life to thrive.

It's the same when "remodeling" an existing aquarium. I've been in a sort of unusual, restless mindset for much of the second half of the year, and I admit, I've been a bit bored with some of the ideas I've been playing with. It seemed right to start shaking things up to move forward.

And, there was no sense in simply trashing all of my well-established tanks while I iterate new ideas. Yeah- there is no sense in completely tearing a tank apart and starting from a pristine, zero biology point. Just utilize elements of the tank (ie; substrate, leaf litter, wood, etc.) which are appropriate for your new idea, and continue on.

There is, of course, a natural analog to this process!

The idea of keeping your aquarium more-or-less "intact" while moving on to a new iteration is just something most of us do- or should do...

In other words, you're kind of over your Southeast Asian Cryptocoryne biotope, and ready to head West to South America. So, rather than tearing up the entire tank, removing all of the plants, the hardscape, the leaves and botanicals, and the substrate, you opt to remove say, only the plants and the driftwood/rocks from the tank; exchange a good quantity of the water.

Woooah! Crazy! You're a real rebel...

I know. I know. Not really. I mean, this isn't exactly earth-shattering. 

On the other hand, in the world of the botanical-method aquarium, the idea of leaving the substrate and leaf litter/botanical "bed" intact as you "remodel" isn't exactly a crazy one. And conceptually, it's sort of replicates what occurs in Nature, doesn't it?

Yeah, think about this for just a second.

As we almost constantly discuss, habitats like flooded forests, meadows, vernal pools, igarape, and swollen streams tend to encompass terrestrial habitats, or go through phases where they are terrestrial habitats for a good part of the year.

In these wild habitats, the leaves, branches, soils, and other botanical materials remain in place, or are added to by dynamic, seasonal processes. For the most part, the soil, branches, and a fair amount of the more "durable" seed pods and such remain present during both phases.

Now, one thing that's unique about the botanical-method approach is that we tend to accept the idea of decomposing materials accumulating in our systems. We understand that they act, to a certain extent, as "fuel" for the micro and macrofauna which reside in the aquarium. The idea of leaving this material in place over the long-term is a crucial component of this approach, IMHO.

As we've discussed repeatedly, just like in Nature, they'll also form the basis of a  complex "food chain", which includes bacterial biofilms, fungi, and minute crustaceans. Each one of these life forms supporting, to some extent, those above...including our fishes.

I have long believed that if you decide to let the botanicals remain in your aquarium to break down and decompose completely, you shouldn't change course by suddenly removing the material all at once...Particularly if you're going to a new version of an existing aquarium.


Well, I think my theory is steeped in the mindset that you've created a little ecosystem, and if you start removing a significant source of someone's food (or for that matter, their home!), there is bound to be a net loss of biota...and this could lead to a disruption of the very biological processes that we aim to foster.

Okay, it's a theory...But I think I might be on to something, maybe? So, like here is my theory in more detail:

Simply look at the botanical-method aquarium (like any aquarium, of course) as a little "microcosm", with processes and life forms dependent upon each other for food, shelter, and other aspects of their existence. And, I really believe that the environment of this type of aquarium, because it relies on botanical materials (leaves, seed pods, etc.), is more signficantly influenced by the amount and composition of said material to "operate" successfully over time.

Just like in natural aquatic ecosystems...

The botanical materials are a real "base" for the little microcosm we create.

And of course, by virtue of the fact that they contain other compounds, like tannins, humic substances, lignin, etc., they also serve to influence the water chemistry of the aquarium, the extent to which is dictated by a number of other things, including the "starting point" of the source water used to fill the tank.


So, in short- I think the presence of botanicals in our aquariums is multi-faceted, highly influential, and of extreme importance for the stability, ecological balance, and efficiency of the tank.

Okay, I might just be torturing this simple idea to death- I admit this point that I'm probably not adding much more to the "recipe" here; likely simply being redundant and even a bit vague...However, I think we need to think about how interesting this simple practice is.

Understand and facilitate these natural processes into your aquariums. Keep that in mind when you "iterate" an aquarium.

If you're months into a tank, and simple don't like the look or performance or whatever- you can easily change it. It's a lot like catching a continuously-running commuter train or subway line, right?

Part of the beauty of the botanical-method aquarium is that you can sort of "pick it up where you are" and "ride it" out for a while, or change the "routing" as you desire! Started your tank as an Amazonian habitat but you're suddenly enamored with a more "Asian" look?

Keep the "operating system" intact, but change out some elements.

Super easy, right?

It is. If you let it be that way.

Evolution is not only fun to watch, it's a lot of fun to manage as well. And it's even more fun to have the option to do both!

Stay patient. Stay curious. Stay motivated. Stay bold...

And Stay Wet.


Scott Fellman

Tannin Aquatics