Constantly Changing. Persistently Evolving...

I make it no secret that the botanical method aquarium is unlike almost any other approach to aquarium keeping currently practiced. Not better. Not the "coolest" (well, possibly...)- just different. To parse all of the many reasons why this approach is so different could literally take years...Oh, wait, it 8 years, to be exact! 

If you take this approach, you simply, literally- need to clear your mind of any preconceived notions that you have about what an aquarium should look like. The aesthetics are unlike anything that you've seen before in the hobby. 

And, over the many years that I've been playing with botanicals, my approaches and processes have changed and evolved, based on my own experiences, and those of our community. The way I approach botanical method aquariums today is definitely a bit different than I have approached them previously.

And that's pretty cool..It's the by-product of years of playing with this stuff; modifying techniques, philosophies, and approaches based upon actual practice.

My practices are constantly changing...Persistently evolving.

Here are a few examples of the evolution of my practices and approaches over the years. 

As a regular consumer of our content, you likely know of my obsession with varying substrate compositions and what I call "enhancement" of the substrate- you know, adding mixes of various materials to create different aesthetics and function.

Over the years, I've developed a healthy interest in replicating the function and form of substrates found in the wild aquatic habitats of the world. What we had to work with in years past in the hobby was simply based upon what the manufacturers had available. I felt that, although these materials are overall great, there was a lot of room for improvement- and some evolution based upon what types of materials are found in actual wild aquatic habitats.

My evolution was based upon really studying the wild habitats and asking myself how I can replicate their function in my tanks. A big chunk of this understanding came from studying how substrate materials in the wild aggregate and accumulate; where they come from, and what they do for the overall aquatic ecosystem.

I'm fascinated with this stuff partly because substrates and the materials which comprise them are so intimately tied to the overall ecology of the aquatic environments in which they are found. Terrestrial materials, like soils, leaves, and bits of decomposing botanical materials become an important component of the substrate, and add to the biological function and diversity.

Now, 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 on 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!

How do these materials find their way into aquatic ecosystems?

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. These materials can profoundly influence water chemistry,  based on the ionic, mineral, and physical concentrations of materials that are dissolved into the water. And it varies based on water velocities and such. 

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 arrive-and stay- in the aquatic ecosystems.

Forest floors...Fascinating ecosystems in their own right, yet even more compelling when they're  flooded. 

And what accumulates on dry forest floors?

Branches, stems, and other materials from trees and shrubs. When the waters return, these formerly terrestrial materials become an integral part of the (now) aquatic environment. This is a really, really important thing to think of when we aquascape or contemplate who we will use botanical materials like the aforementioned stems and branches. They impact both function and aesthetics of an aquarium...Yes, what we call "functional aesthetics" rears its head again!

There is no real rhyme or reason as to why stuff orients itself the way it does. I mean, branches fall off the trees, a process initiated by either rain or wind, and just land "wherever." Which means that we as hobbyists would be perfectly okay just sort of tossing materials in and walking away! Now, I know this is actually aquascaping heresy- Not one serious 'scaper would ever do that...right?

I'm not so sure why they wouldn't.  Look at Nature...

I mean, what's wrong with sort of randomly scattering stems, twigs, and branches in your aquascape? It's a near-perfect replication of what happens in Nature. Now, I realize that a glass or acrylic box of water is NOT nature, and there are things like "scale" and "ratio" and all of that "gobbldeygook" that hardcore 'scaping snobs will hit you over the head with...

But Nature doesn't give a shit about some competition aquascaper's "rules"- and Nature is pretty damn inspiring, right? There is a beauty in the brutal reality of randomness. I mean, sure, the position of stones in an "Iwagumi" is beautiful...but it's hardly what I'd describe as "natural."

 We talk a lot about "microhabitats" in Nature; little areas of tropical habitats where unique physical, environmental and biological characteristics converge based on a set of factors found in the locale. Factors which determine not only how they look, but how they function, as well.

The complexity and additional "microhabitats" they create are compelling and interesting. And they are very useful for shelltering baby fishes, breeding Apistogramma, Poecilocharaxcatfishes, Dicosssus, an other small, shy fishes which are common in these habitats. 

Small root bundles and twigs are not traditionally items you can find at the local fish store or online. I mean, youcan, but there hasn't been a huge amount of demand for them in the aquascaping world lately...although my 'scape scene contacts tell me that twigs are becoming more and more popular with serious aquascapers for "detailed work" this bodes well for those of us with less artistic, more functional intentions!

Except we don't glue shit together. 

When I see aquascapers glue wood together, it makes me want to vomit. I know, I'm an asshole for feeling that way, but it's incredibly lame IMHO. Just fit the shit together with leverage and gravity, like your grandparents did, or keep looking for that perfect piece. Seriously! You don't need to glue to make wood look "cool."  

You're not a reefer gluing coral frags to rock. There is no "need" to do this. 

Relax and just put it together as best as Nature will allow.

Okay, micro rant over!

Let's get back to discussing natural materials and how we've come to include them in our tanks just a bit more...

Like, roots.

In flooded forests, roots are generally found in the very top layers of the soil, where the most minerals are. In fact, in some areas, studies indicated that as much as 99% of the root mass in these habitats was in the top 20cm of substrate! Low nutrient availability in the Amazonian forests is partially the reason for this. And since much of that root mass becomes submerged during seasonal inundation, it becomes obvious that this is a unique habitat.

So, ecological reasons aside, what are some things we as hobbyists can take away from this?  

We can embrace the fact that most of these finer materials will function in our aquairums as they do in Nature, sequestering sediments, retaining substrate, and recruiting epiphytic materials which fishes will forage, hide, and spawn among.

Functional aesthetics.

And let's talk about preparation a bit.

I'm at a phase in my aquarium "career" with regards to botanicals in which I feel it is less and less necessary to worry about extensively preparing my botanical materials for use in my tanks. In essence, my main preparation "technique" is to rinse the items briefly in freshwater, followed by a boil until they are saturated and stay submerged.

It's less and less about "cleaning them" and more and more about getting them to  stay down in my aquairums. And to be perfectly honest, if the materials would actually sink immediately and stay down, I think my "preparation" would simply consist of a good rinse!

What's the reason for this "evolution" of my preparation technique? Well, part of it is because I've started to realize that virtually every botanical item which I use in my work is essentially "clean"- that is, not polluted or otherwise contaminated. Generally, most of the items I use may simply have some "dirt" on their surfaces. I typically will not use botanical items which have bird droppings, insect eggs, or other obvious contaminants present. 

The reality is that, in over 20 years of playing with botanicals, I simply cannot attribute a single fish death to the use of improperly prepared botanical materials!

It's really more about the sourcing, to me. 

Naturally collected materials, air or sun-dried over time are just not an issue. However, when you obtain materials from unvetted sources, you cannot be sure what her original intended use was. For years, the "hack" I've seen was hobbyists purchasing dried botanical materials from craft stores...And these are the people I've seen the most issues with. 

The problem is that materials intended to be used in craft projects are typically chemically preserved or treated with varnishes or other materials...and these are simply deadly to aquatic life.

Feel free to experiment with all sorts of carefully collected natural materials, but I would simply avoid purchasing them from sources which you cannot thoroughly vet. The price of such "hacks" may be the deaths of your fishes.

Another reason I'm less "anal" about preparation of my botanicals and wood and such is that these materials contain a lot of organic materials which are likely "catalysts" for ecological processes. I know, that's vague and oddly unscientific, but it makes sense, when you think about it.

"Organics" are simply incorporated into the aqueous environment, and help foster the growth of a variety of organisms, from fungi to bacterial biofilms and more.  IMHO, they are helpful to create an underwater ecology in your aquirium.  It's no longer a concern of mine that botanicals being added to my aquairums need to be essentially "sterile."

Ecology is the primary motivation for me when it comes to adding botanicals to my tanks- specifically, helping to foster an underwater ecology which will provide the inhabitants with supplemental food and nutrient processing. So, trying to keep things impeccably clean when setting up an ecology first, botanical method aquarium is downright counterproductive, IMHO.

And I have a hunch that a lot of our fear of introducing extraneous "stuff" into our tanks via botanicals was as a result of my excessive paranoia back in 2015, in our earliest days- when I was very concerned about some hobbyist simply dumping a bunch  of our fresh botanicals into his/her tank and ending up with...well, what?

A tank with a little bid of turbidity? Darkly tinted water? Some fungal and biofilm-encrusted seed pods and leaves? Detritus from their tissues?

All things that we've come to not only accept, but to expect and to even celebrate as a normal part of our practice. I mean, man, there is literally an explosion of hashtags used on instagram weekly celebrating shit that I used to have to beat you over the head about to convince you that these things were normal: "Detritus Thursday", "Fungal Friday", etc. 

And, isn't this what you see in wild aquatic habitats?

None of these things are "bad." We're beyond these concerns that were partially rooted in fear, and the other part in our desire to fit in with the mainstream hobby crowd's aesthetic preferences. We've finally accepted that our "normal" is very different from almost every other hobby specialty's view of "normal." 

My development, use, and marketing of our NatureBase line of sedimented substrates reflected another big step in my growing confidence about what is "normal: in our world. These substrates are filled with materials which will make your water turbid for a while...and we absolutely DON'T recommend any sort of preparation before using them. 

Your tank WILL get cloudy for a few days...Absolutely part of the process. I remember a lot of sleepless nights, discussions with Johnny Citotti and Jake Adams before launching the product, and just convincing myself that it was okay to convince fellow hobbyists to...relax bit about this stuff and embrace it, in exchange for the manifold benefits of utilizing more truly natural substrate materials.

The entire botanical method aquarium movement has been, and likely will continue to be- an exercise in stepping out of our hobby "comfort zones" on a regular basis. Trying out ideas which have long been contrary to mainstream  aquairum hobby practice and philosophy. Ideas and practices which question and challenge the "status quo", and seem to go against a century of aquarium work, in favor of embracing the way Nature has done things for eons.

It's a big "ask", but you keep accepting it...and we've all grown together as a result. 

Another seismic shift (in my head, anyways...) is my acceptance that... leaves are leaves. Yeah, seriously. Wether they come from the rainforest of Borneo or the mountains of West Virginia, leaves are essentially similar to each other. Sure, soem look different, or perhaps might have different concentrations of compounds within their tissues...yet they're all fundamentally the same. They perform the same function for the tree, and "behave" similarly when submerged in water. 

A Catappa leaf from Malaysia, Jackfruit leaf from India, or a Live Oak leaf from Southern California are more alike than they are dissimilar. Other than having slightly different concentrations of tannins (and even that is possibly minimal), a leaf is a leaf. To convene ourselves otherwise is kind of funny, actually.

I did for a long time. I was 100% convinced that the leaves I was painstakingly sourcing from remote corners of the globe were somehow better than our Native Magnolia or Live Oak or whatever. The reality is that, other than some exotic sounding names, a morphology that might be different, or a good story about where they  come from, the "advantages" of most "exotic" leaves over "domestically sourced" leaves  ( or leaves from wherever you come from) are really minimal at best.

Trust me- no Catappa leaves find their way into tributaries of the Orinoco river. It's Ficus, Havea leaves, various palms, etc. 

But not Catappa, Guava, or Jackfruit. 

And if they did, they likely impact the water chemistry or ecology no differently.

Leaves are leaves. In fact, ecologically, they all essentially do the same thing, just on a different "timetable." Trees in tropical deciduous forests lose their leaves in the dry season and regrow them in the rainy season, whereas, temperate deciduous forests, trees lose their leaves in the fall and regrow them in the spring.

In the moist forests close to the equator, the climate is warm and there is plenty of rainfall all year round. In this environment there is no reason for the trees to drop their leaves at any particular time of year, so the forest stays green year round. 

Trees from temperate climate zones lose leaves regularly during certain times of the year and then regrow them., and must take a fairly precise cue from their environment. In the mid and high latitudes, if trees put the leaves out too early in the year, these may be damaged by frost and valuable nutrients lost, because the tree cannot easily reclaim nutrients from a frost-bitten leaf.

Yeah, leaves...They perform similar functions for their trees, regardless of where they come from.

The morphological differences are often subtle, and sometimes inconsistent:

It has long been recognized by science that tropical forests are dominated by evergreen trees that have leaves with "complete" margins, whereas trees of temperate forests tend to have deciduous leaves with toothed or lobed margins.

Maybe leaves from different habitats and environments  look a bit different, and fall at different times...but that's really about it... 

I'm sure that this is not an "absolute" sure- there ARE trees which have leaves with higher concentrations of tannins, etc than others...However, by and large, there are not all that many compelling arguments to favor "exotic" leaves from faraway places over the ones you can source locally! 

Sure, soem botanist somewhere could school my on over-generalizing this, but in the aquairum world, I'm not certain one could successfully prove that you MUST use "Pango Pango leaves" from Cameroon to be successful with botanical method aquariums. Now, could one argue that there are some subtle chemical ben efiots to fishes from these regions by using "local" botanicals in their tanks? Maybe. But by and large, I just don't think so anymore.

So,as a hobbyist and vendor, I'm not completely engrossed by chasing every exotic sounding leaf out there anymore. 

I may offer limited quantities of the "big three" in the future, but I feel less and less compelled to do so. Trying to be the aquarium world's "catalogue" of tropical leaves for aquariums long ago lost its luster, among the realities of supply chain issues, tariffs, and unreliable producers. Let other vendors chase the dollars. I'm going to chase my ideas...and use whatever materials I see fit for purpose- regardless of their origin.

Constantly changing. Persistently Evolving.


We're in an amazing time right now. For the first time in years, I personally feel that the idea of botanical method aquariums has moved out of it's obscure, "fringe-culture-like" parking spot in the fish world, and into the light of the mainstream. 

And it's all because of YOU! Sure, many of you were playing with "blackwater" tanks before, but if your experience was anything like mine, you were sort of viewed as a mildly eccentric hobbyist playing with a little "side thing"- a passing fancy that you'd eventually "get over.." 

Well, I think that is changing a lot now. We're seeing a community of what was once widely scattered hobbyists starting to come together and share ideas, technique, pictures, inspiration with other equally as obsessed hobbyists. This is an amazing thing to me, and to be able to witness it firsthand is incredible! It's been a renaissance of sorts for this once-neglected aspect of the hobby.

Another think that I think is interesting is that we, as a community, are viewing our aquariums as "habitats" more than ever before. We  seem to have broken through the mindset of creating aquariums only based on an aesthetic WE like, and fitting the fishes into it, as opposed to creating aquariums with specialized habitats for specific fishes. 

And we're not afraid to make little detours- small changes. And, not all of them need be intentional. Things happening in unexpected ways are what can propel the hobby forward.

Everything doesn't have to follow a plan.

A detour can be amazing.

However, if your looking for a specific result and go too far in a different direction, it's often a recipe for frustration for those of us not prepared of it. Sure, many of us can simply "go with the flow" and accept the changes we made as part of the process, but the aquarist with a very pure vision and course will work through such self-created deviations until he or she gets to the destination.

Many find this completely frustrating.

Others find this a compelling part of the creative process.

Pretty much every major breakthrough I've encountered in my hobby "practice" has been the result of me "breaking pattern" and trying something fairly radically new...You know, a big remake of an aquarium....Trying a new manipulation of the environment, etc.

And of course, the thing which maintains the "breakthrough?"


I've always had this thing about repetition and doing the same stuff over and over agin in my aquarium practice. It's one of the real "truisms", to me, about fish keeping: Once you've gotten in a groove, in terms of husbandry routines, it's great to just do the same thing over and over again. 


Yes, I beat the shit out of that idea fairly regularly, right?

Now, notice that I'm not talking about doing the same thing over and over when it comes to ideas...Nope. I'm of the opinion that you should do all sorts of crazy things when it comes to concepts and experiments.

 One thing that was sort of "experimental" for many years in my world was the idea of NOT removing decomposing botanical materials from my tanks. You know, flat-out siphoning stuff out, lest it do "something" to the water quality in my aquariums.

It was a big deal about 20 years ago...People thought I was crazy for talking about leaving leaves and botnaicals in the tank until they fully decomposed. I was told that if I didn't remove this stuff, all sorts of horrifying outcomes would ensue. Yet, in the back of my mind, I thought to myself, "If the whole idea of botanical method aquariums is to facilitate an ecosystem within the tank, wouldn't removing a significant source of the ecology (ie; decomposing leaves and botanical detritus) be MORE negative than leaving iot in the tank to be "worked" by the resident life forms at various levels?

So I left the stuff in...

Never had any "bad" results...

It really wasn't that surprising, in actuality.

I figured that this would actually be beneficial to the aquairum...My theory was 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 was a theory...But I think I am 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...

Detritus...the nemesis of the hobby...not all that bad, really..

It's all about not simply accepting the generally held hobby "truisms" as "gospel" in EVERY situation. Experimenting and considering stuff in context is important. 

Change and variation is inevitable and important in the hobby. Being open minded about things is vital. 

The processes of evolution, change and disruption which occur in natural aquatic habitats- and in our aquariums- are important on many levels. They encourage ecological diversity, create new niches, and revitalize the biome. Changes can be viewed as frightening, damaging events...Or, we can consider them necessary processes which contribute to the very survival of aquatic ecosystems.

Think about that the next time you hesitate to experiment with that new idea, or play a hunch that you might have. Remember that there is always a bit of discomfort, trepidation, and risk when you make changes or conduct bold experiments. 

Goes with the territory, really.

However, once you get out of that comfort zone, you're really living...and the fear will give way to exhilaration and maybe even triumph! Because in the aquarium hobby, the bleeding edge is when you're constantly changing, and patiently evolving.

Stay Brave. Stay persistent. Stay curious. Stay thoughtful. Stay creative...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




One of the things that drives most hobbyists crazy is when "stuff" gets blown around, covered or moved about in the aquarium. It can be because of strong current, the activity of fishes, or simply overgrown by plants. I understand the annoyance that many hobbyists feel; I recall this same aggravating feeling in many reef tanks where I had high flow and sand on the bottom- almost always a combination for annoyance! 

I mean, I get it. We have what feel is a carefully thought-out aquascape, looking exactly how we expected it would after setup. Yet, despite our ideas and thoughts, stuff moves around in the aquarium. It's something we can either accept, or modify in our aquariums, depending upon our preferences.


Yet, movement and "covering" of various materials by sediments, biofilms, etc., which accumulate on the substrate in natural habitats are everyday occurrences, and they help forge a very dynamic ecosystem. And they are constantly creating new opportunities for the fishes which reside in them to exploit.  

When you think about how materials "get around" in the wild aquatic habitats, there are a few factors which influence both the accumulation and distribution of them. In many topical streams, the water depth and intensity of the flow changes during periods of rain and runoff, creating significant re-distribution of the materials which accumulate on the bottom, such as leaves, branches, seed pods, and the like.

Larger, more "hefty" materials, such as branches, submerged logs, etc., will tend to move less frequently, and in many instances, they'll remain stationary, providing a physical diversion for water as substrate materials accumulate around them.

A "dam", of sorts, if you will.

And this creates known structures within streams in areas like Amazonia, which are known to have existed for many years. Semi-permanent aquatic features within the streams, which influence not only the physical and chemical environment, but the very habits and abundance of the fishes which reside there.

Most of the small stuff, like leaves, tend to move around quite a bit... One might say that the "material changes" created by this movement of materials can have significant implications for fishes. As we've talked about before, they follow the food, often existing in, and subsisting off of what they can find in these areas.

New accumulations of leaves, detritus, and other materials benefit the entire ecosystem.

In the case of our aquariums, this "redistribution" of material can create interesting opportunities to not only switch up the aesthetics of our tanks, but to provide new and unique little physical areas for many of the fishes we keep.

And yeah, the creation of new feeding opportunities for life forms at all levels is a positive which simply cannot be overstated! As hobbyists, we tend to lament changes to the aquascape of our tanks caused by things outside of our control, and consider them to be a huge inconvenience, when in reality, they're not only facsimile of very natural dynamic processes-they are fundamental to their evolution.

The benthic microfauna which our fishes tend to feed on also are affected by this phenomenon, and as mentioned above, the fishes tend to "follow the food", making this a case of the fishes adapting to a changing environment. And perhaps...maybe...the idea of fishes sort of having to constantly adjust to a changing physical environment could be some sort of "trigger", hidden deep in their genetic code, that perhaps stimulates overall health, immunity or spawning?

Something in their "programing" that says, "You're at home..." Perhaps something which triggers specific adaptive behaviors?

I find this possibility fascinating, because we can learn more about our fishes' behaviors, and create really interesting habitats for them simply by adding botanicals to our aquariums and allowing them to "do their own thing"- to break apart as they decompose, move about as we change water or conduct maintenance activities, or add new pieces from time to time.

Again, just like Nature.

We just need to "get over ourselves" on this aesthetic thing!

Another mental shift? Yeah, it is. An easy one, but one that we need make, really.

Like any environment, botanical/ leaf litter beds have their own "rhythm", fostering substantial communities of fishes. The dynamic behind this biotope can best be summarized in this interesting excerpt from an academic paper on blackwater leaf-litter communities by biologist Peter Alan Henderson, that is useful for those of us attempting to replicate these communities in our aquaria:

" 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, different species inhabit different sections of the leaf litter beds. As aquarists, we should consider this when creating and stocking our botanical-style aquariums.

It  just makes sense, right?


So, when you're attempting to replicate such an environment, consider how the fishes would utilize each of the materials you're working with. For example, leaf litter areas would be an idea shelter for many juvenile fishes, catfishes, and even young cichlids to shelter among.

Submerged branches, larger seed pods and other botanicals provide territory and areas where fishes can forage for macrophytes (algal growths which occur on the surfaces of these materials). Fish selection can be influenced as much by the materials you're using to 'scape the tank as anything else, when you think about it!

And it's not just fishes, of course. It's a multitude of life forms.

There are numerous life forms which are found on ad among these materials as well, such as fungal growths, bacterial biofilms, etc. which we likely never really consider, yet are found in abundance in nature and in the aquarium, 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. Yes, you heard. Freshwater sponges! 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. Some are truly incredible looking organisms!

(Spongilla lacustris Image by Kirt Onthank. Used under CC-BY SA 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!

Oh, cool!

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  freshwater 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!

We've encountered them in reef tanks for many years...I wonder if they could ultimately find their way into our botanical-style aquariums as well?  Perhaps they already have. Have any of you encountered one before in your tanks?

The big takeaway from all of this: A botanical bed in our aquariums and in Nature is a physical structure, ephemeral though it may be- which functions just like an aggregation of branches, or a reef, rock piles, or other features would in the wild benthic environment, although perhaps even "looser" and more dynamic.

Stuff gets redistributed, covered, and often breaks down over time. Exactly like what happens in Nature.

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

It's all brought about by the dynamic process of movement.

Perhaps instead of looking at the movement of stuff in our tanks as an annoyance, we might enjoy it a lot more if we look at it as an opportunity! An opportunity to learn more about the behaviors and life styles of our fishes and their ever-changing environment.

Stay observant. Stay creative. Stay excited. Stay open-minded...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




Botanical materials in the wild...and in the aquarium: Influences and Impacts.

As you know, we've spent the better part of the past 6 years talking about every aspect of the botanical-style aquarium that we can think of. We've talked about techniques, approaches, ideas, etc. And we've spent a lot of time sharing information about wild aquatic habitats that we might be interested in replicating in both form and function.

However, I think we haven't spent as much time as we should talking about how botanicals "behave" in wild aquatic habitats.  Much of this stuff has implications for those of us who are interested in replicating these habitats in our aquariums. So, let's dive in a bit more on this topic today!

Among the trees of the flooded forests, after the fruits mature (which occurs at high water levels), seeds will fall into the water and may float on the surface or be submerged for a number of weeks. Ecologists believe that the seed production of the trees coincides with the flood pulses, which facilitates their dispersal by water movement, and by the actions of fish.

Interestingly, scientists postulate that these floating or sinking seeds, which  germinate and establish seedlings after the flood waters recede, do very well, sprouting and establishing themselves quickly, and are not severely affected by waterlogging in most species.

So, within their cycle of life, the trees take advantage of the water as part of their ecological adaptation. Trees in these areas have developed specialized morphologies, such as advantageous roots, butress systems and stilt roots.

 In a lot of wild aquatic habitats where leaf litter and other allochthonous materials accumulate, there are a number of factors which control the density, size, and type of materials which are deposited in streams and such. The flow rate of the water within these habitats determines a lot of things, such as the size of the leaves and other botanical materials  and where in the stream they are deposited. 

I often wonder how much the fallen leaves and seed pods impact the water chemistry in a given stream, pond, or section of an Amazonian flooded forest. I know that studies have been done in which ecologists have measured dissolved oxygen and conductivity, as well as pH. However, those readings only give us so much information.

We hear a lot of discussion about blackwater habitats among hobbyists, and the implications for our aquariums. And part of the game here is understanding what it is that makes this a blackwater river system to begin with. We often hear that blackwater is "low in nutrients." 

What exactly does this mean?

One study concluded that the Rio Negro is a blackwater river in large part because the very low nutrient concentrations of the soils that drain into it have arisen as a result of "several cycles of weathering, erosion, and sedimentation." In other words, there's not a whole lot of minerals and nutrients left in the soils to dissolve into the water to any meaningful extent!

Black-waters, drain from older rocks in areas like the Negro river, result from dissolved fulvic and humic substances, present small amounts of suspended sediment, lower pH (4.0 to 6.0) and dissolved elements. Yes, highly leached tropical environments where most of the soluble elements are quickly removed by heavy rainfall.

Perhaps...another reason (besides the previously cited limitation of light penetration) why aquatic plants are rather scare in these waters? It would appear that the bulk of the nutrients found in these blackwaters are likely dissolved into the aquatic environment by decomposing botanical materials, such as leaves, branches, etc.

Why does that sound familiar?

Besides the color, of course, the defining characteristics of blackwater rivers are pH values in the range of 4-5, low electrical conductivity, and minimal mineral content. Dissolved minerals, such as  Ca, Mg, K, and Na are negligible. And with these low amounts of dissolved minerals come unique challenges for the animals who reside in these systems.

How do fishes survive and thrive in these rather extreme habitats?

It's long been known that fishes are well adapted to their natural habitats, particularly the more extreme ones. And this was borne out in a recent study of the Cardinal Tetra. Lab results suggest that humic substances  protect cardinal tetras in the soft, acidic water in which they resides by preventing excessive sodium loss and stimulating calcium uptake to ensure proper homeostasis.

This is pretty extraordinary, as the humic substances found in the water actually enable the fishes to survive in this highly acidic water which is devoid of much mineral content typically needed for fishes to survive!

And of course, botanicals, leaves, and wood typically have an abundance of these humic substances, right? They are useful for more than just an interesting and unique aesthetic effect! There is a lot of room for research about influencing the overall environment in our aquariums here! I think we've barely scratched the surface of the potential for utilizing botanicals in our aquariums.

This is another one of those foundational aspects of the natural style of aquarium that we espouse. The understanding that processes like decomposition and physical transformation of the materials that we utilize our tanks are normal, expected, and beautiful things requires us to make mental shifts.

Botanical materials don't have nearly as much impact on the water parameters (other than say, conductivity and dissolved oxygen) as the soils do. These waters have high concentrations of humic and fulvic acids derived from sandy "hydromorphic podsols" prevalent in the region.  However, these allochthonous materials have huge impact on the ecology of these systems!

Leaf litter, as one might suspect, is of huge importance in these ecosystems. Especially in smaller tributaries. In one study which I came across, it was concluded that, "The smaller the stream, the more dependent the biota is on leaf litter habitats and allocthonous energy derived directly or indirectly from the forest." (Kemenes and Forsberg)

From the same study, it was concluded that the substrate of the aquatic habitat had significant influence on the feeding habits of the fishes which resided in them: 

"The biomass of allocthonous insectivore increased in channels with a higher percentage of sandy bottom substrate. Detritivorous insectivore biomass, in contrast, increased significantly in channels with a higher percentage of leaf substrate. General insectivores tended to increase in streams with higher proportions of leafy substrate, too.

Whats the implication for us as hobbyists? Well, for one thing, we can set up the benthic environment in our tanks to represent the appropriate environment for the fishes which we want to keep in them. Simple as that!

t's as much about function as anything else. And, about pushing into some new directions. The unorthodox aesthetics of these unusual aquariums we play with just happen to be an interesting "by-product" of theirfunction.

I personally think that almost every botanical-style aquarium can benefit from the presence of leaves. As we've discussed numerous times, leaves are the "operating system" of many natural habitats (ecology-wise), and perform a similar role in the aquarium.

The presence of botanical materials such as leaves in these aquatic habitats is fundamental. Leaves and other botanicals are extremely pervasive in almost every type of aquatic habitat.

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.

Now, interestingly enough, 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!

Our botanical-style aquariums are not "set-and-forget" systems, and require basic maintenance (water exchanges, regular water testing, filter media replacement/cleaning), like any other aquarium.  They do have one unique "requirement" as part of their ongoing maintenance which other types of aquariums seem to nothave: The "topping off" of botanicals as they break down.

The "topping off" of botanicals in your tank accomplishes a number of things: first, it creates a certain degree of environmental continuity- keeping things consistent from a "botanical capacity" standpoint. Over time, you have the opportunity to establish a "baseline" of water parameters, knowing how many of what to add to keep things more-or-less consistent, which could make the regular "topping off" of botanicals a bit more of a "science" in addition to an "art."

In addition, it keeps a consistent aesthetic "vibe" in your aquarium. Consistent, in that you can keep the sort of "look" you have, while making subtle- or even less-than-subtle "enhancements" as desired. 

Yeah, dynamic.

And, of course, "topping off" botanicals helps keeps you more intimately "in touch" with your aquarium, much in the same way a planted tank enthusiast would by trimming plants, or a reefer while making frags. When you're actively involved in the "operation" of your aquarium, you simply notice more. You can also learn more; appreciate the subtle, yet obvious changes which arise on an almost daily basis in our botanical-style aquariums.

I dare say that one of the things I enjoy doing most with my blackwater, botanical-style aquariums (besides just observing them, of course) is to "top off" the botanical supply from time to time. I feel that it not only gives me a sense of "actively participating" in the aquarium- it provides a sense that you're doing something nature has done for eons; something very "primal" and essential. Even the prep process is engaging.

Think about the materials which accumulate in natural aquatic habitats, and how they actually end up in them, and it makes you think about this in a very different context. A more "holistic" context that can make your experience that much more rewarding. Botanicals should be viewed as "consumables" in our hobby- much like activated carbon, filter pads, etc.- they simply don't last indefinitely.

Many seed pods and similar botanicals contain a substance known as lignin. Lignin is defined as a group of organic polymers which are essentially the structural materials which support the tissues of vascular plants. They are common in bark, wood, and yeah- seed pods, providing protection from rotting and structural rigidity.

In other words, they make seed pods kinda tough.

Yet, not permanent.

That being said, they are typically broken down by fungi and bacteria in aquatic environments. Inputs of terrestrial materials like leaf litter and seed pods into aquatic habitats can leach dissolved organic carbon (DOC), rich in lignin and cellulose. Factors like light intensity, mineral hardness, and the composition of the aforementioned bacterial /fungal community all affect the degree to which this material is broken down into its constituent parts in this environment.

Hmm...something we've kind of known for a while, right?

So, lignin is a major component of the "stuff" that's leached into our aquatic environments, along with that other big "player"- tannin.

Tannins, according to chemists, are a group of "astringent biomolecules" that bind to and precipitate proteins and other organic compounds. They're in almost every plant around, and are thought to play a role in protecting the plants from predation and potentially aid in their growth. As you might imagine, they are super-abundant in...leaves. In fact, it's thought that tannins comprise as much as 50% of the dry weight of leaves!


And of course, tannins in leaves, wood, soils, and plant materials tend to be highly water soluble, creating our beloved blackwater as they decompose. As the tannins leach into the water, they create that transparent, yet darkly-stained water we love so much!  

In simplified terms, blackwater tends to occur when the rate of "carbon fixation" (photosynthesis) and its partial decay to soluble organic acids exceeds its rate of complete decay to carbon dioxide (oxidation).

Chew on that for a bit...Try to really wrap your head around it...

And sometimes, the research you do on these topics can unlock some interesting tangential information which can be applied to our work in aquairums...

Interesting tidbit of information from science: For those of you weirdos who like using wood, leaves and such in your aquariums, but hate the brown water (yeah, there are a few of you)- you can add baking soda to the water that you soak your wood and such in to accelerate the leaching process, as more alkaline solutions tend to draw out tannic acid from wood than pH neutral or acidic water does. Or you can simply keep using your 8.4 pH tap water! 

"ARMCHAIR SPECULATION": This might be a good answer to why some people can't get the super dark tint they want for the long term...If you have more alkaline water, those tannins are more quickly pulled out. So you might get an initial burst, but the color won't last all that long...

I think just having a bit more than a superficial understanding of the way botanicals and other materials interact with the aquatic environment, and how we can embrace and replicate these systems in our own aquariums is really important to the hobby. The real message here is to not be afraid of learning about seemingly complex chemical and biological nuances of blackwater systems, and to apply some of this knowledge to our aquatic practice.

It can seem a bit  intimidating at first, perhaps even a bit contrarian to "conventional aquarium practice", but if you force yourself beyond just the basic hobby-oriented material out there on these topics (hint once again: There aren't many!), there is literally a whole world of stuff you can learn about!

It starts by simply looking at Nature as an overall inspiration...

Wondering why the aquatic habitats we're looking at appear the way they do, and what processes create them. And rather than editing out the "undesirable" (by mainstream aquarium hobby standards) elements, we embrace as many of the elements as possible, try to figure out what benefits they bring, and how we can recreate them functionally in our closed aquarium systems.

There are no "flaws" in Nature's work, because Nature doesn't seek to satisfy observers. It seeks to evolve and change and grow. It looks the way it does because it's the sum total of the processes which occur to foster life and evolution.

We as hobbyists need to evolve and change and grow, ourselves.

We need to let go of our long-held beliefs about what truly is considered "beautiful." We need to study and understand the elegant way Nature does things- and just why natural aquatic habitats look the way they do.  To look at things in context.  To understand what kinds of outside influences, pressures, and threats these habitats face.

And, when we attempt replicate these functions in our aquariums, we're helping to grow this unique segment of the aquarium hobby.

Please make that effort to continue to educate yourself and get really smart about this stuff...And share what you learn on your journey- all of it- the good and the occasional bad. It helps grow the hobby, foster a viable movement, and helps your fellow hobbyists!

Stay studious. Stay thoughtful. Stay inquisitive. Stay creative. Stay engaged...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Keeping it together: The beauty of "buttress roots" and their function in the flooded forests...

There is something incredibly compelling about the way terrestrial trees and shrubs interact with the aquatic environment. This is a surprisingly dynamic, highly inter-dependent relationship which has rarely been discussed in aquarium circles.

Let's have that talk!

We have talked a lot about roots before...They are structures which are so important in so many ways to these ecosystems, in both their terrestrial and aquatic phases.

Not only do they help "secure the soils" from falling away, they foster epiphytic algae, fungal growth, and biofilms, which supplement the foods of the resident fishes. And of course, they provide a physical habitat for fishes to forage, seek shelter, and reproduce among. In short, these roots create a unique "microhabitat" which harbors a diversity of life.

And they look pretty aesthetically cool, too!

So yeah- this makes them an irresistible subject for a natural-looking- and functioning- aquascape!. And relatively easy to execute, too!

With a variety of interesting natural materials readily available to us as hobbyists, it's easier than ever to recreate these habitats in as detailed a version as you care to do. 

As usual with my ramblings, this blog has become yet another homage to roots and other forest features, and how they function in the transitional aquatic habitats we love so much.

One of the foundational root types that we can replicate in or aquarium works what botanists call "buttress roots." Not only are these interesting structures to replicate in our aquariums, they are an important component of the ecosystems which make up the flooded forests, particularly in areas like Amazonia.

Buttress roots are large, very wide roots that help keep shallow-rooted forest trees from toppling over. They are commonly associated with nutrient-poor soils (you know, like the kinds you see in the igapo or varzea ecosytems). These roots also serve to take uptake nutrients are available in these podzolic soils.

The buttress roots of various species of forest trees often weave in and out of each other horizontally, and create a vast network which serves to keep many trees in the forest from toppling over. And since these habitats often flood during the rainy season, buttress roots help stabilize the trees and retain soils during this inundation.

Isn't that interesting? Even the trees have made adaptations over eons which allow them to survive under these harsh conditions! As you might suspect, the "white-water" flooded forests (Varzea) tend to be richer in species diversity and density than the less nutrient-dense blackwater-flooded Igapo forests. Seems like everything in these ecosystems is a function of nutrient availability, isn't it?

And the sandy soil which comprises these habitats is low in nutrients, such as phosphorus, potassium, calcium, and magnesium. Ecologists will tell you that the soil also has a "high infection rate", or density, of fungi, and consists of a lot of fine roots in the upper layer of the soil.

The network of fine roots helps these forests uptake nutrients in these nutrient- poor conditions. And even more interesting, studies have shown that decomposition of materials can take several years in the deep litter layer on the forest floor.

In addition to being nutrient poor, the sandy soil does not retain water very well, which can lead to drought after the inundation period is over. It's another example of the intricate relationship between land and water, and the way terrestrial and aquatic habitats work together. 

Because the flood pulses are so predictable, eons of this process has led to adaptations by various forest trees to withstand them, as well as to depend upon various species of fishes ('frugivores") to help disperse seeds throughout the forest by consuming and pooping them out!

Ecologists have further determined that the distribution of various species of trees in these forests may be largely determined by the ability of their seedlings to tolerate periods of submergence and limited light that penetrates the canopy through the water column.

(Cariniana legalis tree. Image by mauroguanandi, used under CC BY 2.0)

In fact, in remarkable adaptation to this environment, seedlings may be completely submerged for several months, and many species can tolerate several weeks of complete submergence in a state of "rest." Most species  in these forests tend to grow during the times year when the forests are flooded, and tend to bear fruit and flower when the waters start to recede.

It's all about adaptation to this incredible, highly variable habitat. 

We talk a lot about food webs in these habitats and how to replicate some of their attributes in our aquariums. Here's another insight into the food webs of these flooded forest habitats to consider, from a paper I found by researcher Mauricio Camargo Zorro:

"Both algae and aquatic macrophytes enter in aquatic food webs mostly in form of detritus (fine and coarse particulate organic matter) or being transported by water flow and settling onto substrates (Winemiller 2004). Particulate organic matter in the stream of rapids and waterfalls is mostly associated with biofilm and epilithic diatoms that grow on rocks, submerged wood, and herbaceous plants and compose the main energy sources for macro invertebrates and other trophic links (Camargo 2009a)."

A lot there, I know. What this does is give us some ideas about facilitating the "in situ" production of supplementary food sources in our aquariums. 

This was what inspired me in a recent home "planted" blackwater aquarium. The interaction between the terrestrial elements and the aquatic ones. Allowing terrestrial leaves to accumulate naturally among the "tree root structure" we have created fosters this more natural-functioning environment.

As these leaves begin to soften and ultimately break down, they foster microbial growth, biofilms, and fungal growths- all of which will provide supplemental foods for the resident fishes...just like what happens in Nature. 

Facilitating these processes- allowing the materials to accumulate naturally and break down "in situ" is a key component of replicating and supporting these microhabitats in our aquariums. The typical aquarium hardscape- artistic and beautiful as it might be, generally replicates the most superficial aesthetic aspects of such habitats, and tends to overlook their function- and the reasons why such habitats form.

Replicating forest structures- like buttress roots and their functions- really helps facilitate more natural biological processes, functions, and behaviors in our fishes! 

The possibilities are endless here! And, as always, the aesthetics are a "collateral benefit" of the process.

And of course, I think it's a call for us to employ some bigger, thicker pieces of wood in our tanks! Now, sure, I can hear some groans. I mean, big, heavy wood has some disadvantages in an aquarium. First, the damn things are...well- BIG- taking up a lot of physical space, and in our case, precious water volume. And the "scale" is a bit different. And, of course, a big, heavy piece of wood is kind of pricy. And physically cumbersome for some.

However, the use of larger pieces of wood- or several pieces of wood aggregated together- can create really interesting structures which can replicate the form and function of buttress roots in the aquarium. 


At the very least, you can try a fairly large piece of aquatic wood (or several smaller pieces, aggregated to form one large piece) some time. I think you might find this sort of arrangement quite fascinating to play with!

Arrange the wood in such a way as to break up the tank space and give the impression that it simply rooted naturally. Let it create barriers for fishes to swim into, and disrupt water flow patterns. Allow it to "cultivate" fungal growth and biofilms on its surfaces, and small pockets where leaves, botanicals, substrate materials, and...detritus can collect.

This is exactly what happens in Nature.

It's fascinating and important for us to understand- at least on a superficial level- the concept of replicating some of the structures and features of these transitional habitats, such as flooded forest floors.

By understanding how these structures work, why the exist, and how they provide a benefit to the organisms which live among them, we will be in an excellent position to incorporate exciting features- such as buttress roots-into our future aquariums!

Stay inspired. Stay educated. Stay bold. Stay creative. Stay thoughtful...

And Stay Wet.


Scott Fellman

Tannin Aquatics