September 25, 2019


Continuity, renewal, stability...and evolution...

As I've loudly and repeatedly announced lately, I've embarked on some "remodels" of some of the aquariums in our office, and it's been a most interesting experience- as it always is. I've taken a slightly different approach to these "makeovers" over time. Specifically, one of the things I've done in recent years is to keep the substrate layers from the existing tanks and "build on them." 

In other words, I'm taking advantage of the well-established substrate layers, complete with their sediments, decomposing leaves and bits of botanicals, and simply building upon them with some additional substrate and leaves. I've done this many times over the years- it's hardly a "game-changing" practice, but it's something not everyone recommends or does.

I believe that preserving and building upon an existing substrate layer provides not only some biological stability (ie; the nitrogen cycle), but it has the added benefit of maintaining some of the ecological diversity and richness created by the beneficial fuana and the materials present within the substrate.  I know many 'hobby old timers" might question the safety- or the merits-of this practice, mentioning things like "disturbing" the bacterial activity" or "releasing toxic gasses", etc. I simply have never experienced any issues of this nature from this practice. Well maintained systems generally are robust and capable of evolving from such disturbances. 

I see way more benefits to this practice than I do any potential issues.

Since I tend to manage the water quality of my aquariums well, I have never had any issues, such as ammonia or nitrite spikes, by doing this- in fresh or saltwater systems. It's a way of maintaining stability- even in an arguably disruptive and destabilizing time!

This idea of "perpetual substrate"- keeping the same substrate layer "going" in successive aquarium iterations- is just one of those things we can do to replicate Nature in an additional way. Huh? Well, think about it for just a second. In Nature, the substrate layer in rivers, streams, and yeah, flooded forests and pools tends to not completely wash away during wet/dry or seasonal cycles.

Oh sure, some of the material comprising the substrate layer may get carried away by currents or other weather dynamics, but for the most part, a good percentage of the material- and the life forms within it- remains.

So, by preserving the substrate and "refreshing" it a bit with some new materials (ie; sand, sediment, gravel, leaves, and botanicals), you're essentially mimicking some aspects of the way Nature functions in these wild habitats. And, from an aquarium management perspective, consider the substrate layer a living organism (or "collective" of living organisms, as it were), and you're sure to look at things a bit differently next time you re-do a tank!

Of course, perpetuating the substrate is almost like persuing "eternal youth"- it's not entirely possible to achieve, but you can embrace the idea of renewal and continuity within your aquarium.

Things change in Nature, but other things are also preserved. Nothing goes to waste.

And yet, one concept about botanical-style aquariums that I can't seem to bring up enough is the idea that many of the habitats we like to represent in our tanks- and the materials which we utilize to 'scape them, are ephemeral. In other words, they are not "permanent" features, in the same way a rock or a piece of wood is-instead, breaking down and decomposing following long-term submersion.

I find the ephemeral quite alluring. 

Leaves, of course, are the ultimate statement of Nature's ephemeral character. Things always change. Nothing lasts forever- at least, not in its original form. Leaves begin to break down and impart organic materials, ranging from lignins to tannins to humic substances- even sugars- into the water.

One interesting observation I’ve made over the years concerning adding leaves to the aquarium and letting them decay: Dead, dried leaves such as those we favor don’t have nearly the impact on water quality, in terms of nitrate, as fresh leaves would (and yeah, I've played with both...). I’ve routinely seen undetectable nitrate levels in aquariums loaded with botanicals. This is largely because dead, dried leaves have depleted the vast majority of stored sugars and other compounds which lead to the production of nitrogenous substances in the confines of the aquarium.

Hence, leaving leaves in to fully decay likely reaches a point when the detritus, which results is essentially inert, consisting of the "skeletonized" sections of leaf tissue which can decay no further. Dead leaves contain largely inert forms of polysaccharides, and are rich in structures like lignin and cellulose. Just keeping overall water quality consistently high is a great practice.

Oh, and doing regular water changes can’t hurt...😆

And, of course, in the aquarium, much like in the natural habitat, the layer of decomposing leaves and botanical matter, colonized by so many organisms, ranging from bacteria to macro invertebrates and insects, is a prime spot for fishes! The most common fishes associated with leaf litter in the wild are species of characins, catfishes and electric knife fishes, followed by our buddies the Cichlids (particularly ApistogrammaCrenicichla,  and Mesonauta species)!

Some species of Rivulus killies are also commonly associated with leaf litter zones, even though they are primarily top-dwelling fishes.  Leaf litter beds are so important for fishes, as they become a refuge for fish providing shelter and food from associated invertebrates.

And of course, the eternal question: How often do you need to replace your leaves?

Well, it's another great question for which there is no "rule" involved. The reality is that you can simply add new leaves on a regular basis, so you'll always be making up for the ones that have decomposed. Some hobbyists like to remove the decomposed leaves, preferring a more "pristine" look. It boils down to aesthetics, really.

Of course, there are those functional and ecological aspects, too...right?

And besides leaves and seed pods, there is that other "stuff" that we all love..Branches, stems...twigs.

Those of us who obsessively study images of the wild tropical habitats we love so much can't help but note that many of the bodies of water which we model our aquariums after are replete with tree branches and stems. Since many of these habitats are ephemeral in nature, they are only filled up with water part of the year.

The remainder of the time, they're essentially dry forest floors.

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!

And, from the perspective of the aquascaper, this dynamic can be either stimulating or challenging...or both, depending upon how you look at it. There is no real rhyme or reason as to which materials orient themselves the way they do. 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 the tank" and walking away!  I'm serious. 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. 

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 shit that hardcore 'scaping snobs will bash you over the head with...

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

Nature is...well...Natural. She's the bomb!

Which begs the question: Who really cares? Do what you like! I I get it. Yet, I still think that we could do a lot worse than literally dropping materials into our tanks (taking into account their size of course) and admiring the randomness of it all.

Look to Nature. And be bold.

Think about maintaining the continuity of an ecosystem and perpetuating biological activity and "structural" randomness.

The "mental stretches" that we talk about incessantly here are still occurring for me, years into this game. With each pic I see of the natural habitats we want to emulate, and every beautiful aquarium that I see come to life from our community, it's inspiring, interesting, and engaging. I'm seeing and experiencing new things, coming up with new ideas, and trying to understand and embrace the processes and aesthetics in a whole new light.

I am happy to see many of you doing the same. Evolving.

What do you have up next?

Sure, embracing some different ideas on the management of aquariums and the aesthetics themselves can seem a bit- well, intimidating at first, but if you force yourself beyond just the basic hobby-oriented mindset out there on these topics, there is a whole world of stuff you can experience and learn about!

And the information you can gain from this process just might have an amazing impact on your aquarium practice; that might just lead to some remarkable breakthroughs that will forever change the hobby!

That's the beauty of continuity, renewal...and stability- all working together.

Stay observant. Stay curious. Stay creative. Stay open-minded...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


September 24, 2019


A salty "sayonara"- or a shift to the future?

As we're entering into the final phases of the brackish water aquarium we set up in  our office more than a year and a half ago, it's time to sort of reflect upon the lessons learned and the joys of the journey.  My decision to take this tank down was very difficult- and only made because it was time to use our limited tank space here to show you something different. I love this tank.

Over the operational lifetime of this tank,  I've noticed some interesting things about the way this tank runs, and how it is so similar to the blackwater systems we're all familiar with by now.

Like our "conventional" (Shit, that's funny to say, huh?) botanical-style systems, the brackish system embraces the same use of decomposing leaves, wood, and botanicals, with the added variables of a rich, "sediment-centric" substrate and the dynamic of specific gravity to contend with. 

Interestingly, however, this type of system runs much like the blackwater, botanical-style systems that we are used to, with the exception that it is far more "nutrient rich" than the blackwater tanks. The dynamics of decomposition and the ephemeral nature of leaves and such in the water are analogous in many respects, as well.

Fungi and bacteria in brackish and saltwater mangrove ecosystems help facilitate the decomposition of mangrove material, just like in their pure freshwater counterparts. Interestingly, in scientific surveys, it's been determined that bacterial counts are generally higher on attached mangrove leaves than they are on freshly-fallen leaf litter, and this is kind of interesting, because ecologists feel that attached, undamaged mangroves leaves don't release much tannin, which, as we know might have some "anti-bacterial" properties. However, it's also been found that materials like humic acid, which are abundant in the mangroves, stimulate phytoplankton growth there. 

Interesting, right?

The leaves of mangroves, as they break down, become subject to both leaching of the compounds in their tissues, as well as microbial breakdown. Compounds like potassium and carbohydrates are commonly leached quickly, followed by...tannins. Fungi are the "first responders" to leaf drop in mangrove communities, followed by bacteria, which serve to break down the leaves further.

So, in summary, you have a very active microbial community in a brackish water aquarium!

And yeah, the water in a brackish system "configured" in this manner is decidedly tinted- largely a function of the mangrove branches and roots, which, as they break down, give off a significant amount of color-producing tannins from their tissues.

It's hardly a secret that mangrove wood, leaves, and bark are loaded with these tannins! In fact, Red Mangrove bark is one of our favorite "secret weapons" for producing incredibly deep tint in all types of aquariums!

The management of a botanical-style brackish tank is really surprisingly similar to that of a typical blackwater aquarium. The biggest difference is the salt and perhaps a greater interest in a deep, very rich substrate. Now, one parameter I changed since the system began was to increase the specific gravity from 1.004 to 1.010 This was done because it is a sort of "sweet spot" that many of the fishes which I am interested in (gobies, rainbow fishes, chromides, mollies, etc.) seem to fare quite well at this slightly higher S.G.


Also, I've made no secret about a desire at some future point to do a brackish system where I slowly push things all the way up to like 1.021 (on the low end of natural seawater specific gravity) and incorporate corals and macro algae into the display, along with marine fishes! And, if I do execute this, the "creep" towards this higher S.G. will be made over a very long period of time (close to a year), so it will be advantageous for the resident fishes to adapt to full-strength marine water slowly. 

So, yeah, you're playing with salt...

Do yourself a favor and splurge on a digital refractometer. Not a "swing arm" hydrometer that breaks easily and goes off-calibration if you look at it wrong, not a conventional refractometer which forces you to "read between the lines" to obtain an accurate reading. No. Splurge on a good piece of gear-spend over one hundred dollars and get a real-deal, name brand piece of lab-quality equipment that will give you precise readings with a minimum of hassle and will last for years...

Do it. You won't regret it at all.

And sure, managing a system that "floats" between two realms (freshwater and marine) seems like a bit of a balancing act, I know..because it is. However, it's not difficult. You simply apply the lessons you've learned playing with all of this crazy botanical-style blackwater stuff we talk about all the time.

Yes, you might kill some stuff, because you may not be used to managing a higher-nutrient brackish water system. You have a number of variables, ranging from the specific gravity to the bioload, to take into consideration. Your skills will be challenged, but the lessons learned in the blackwater, botanical-style aquariums that we're more familiar with will provide you a huge "experience base" that will assist you in navigating the "tinted" brackish water, botanical-style aquarium.

Now, this IS a different type of approach to brackish aquariums. 

However, it's likely not "ground-breaking", in that it's never, ever before been done like this before. I just don't think that t's never been embraced like this before: Met head-on for what it is- what it can be, instead of how we wanted to make it (bright white sand, crystal-clear water, and a few rocks and shells...Nature "edited" to our aesthetic "standards"). Rather, it's an evolution- a step forward out of the artificially-induced restraints of "this is how it's always been done"- another exploration into what the natural environment is REALLY like- and understanding, embracing and appreciating its aesthetics, functionality, and richness.  

I'm proud to have pushed this type of approach, and even prouder that many of you have been inspired to try it as well!

Figuring out how to bring this into our aquariums. That sort of thing.

What really sets our approach apart, besides simply the aesthetics of it all, is the function- which is a "by-product" of us going more "natural" and modeling our aquarium after the actual habitats themselves.

The bottom of this type of habitat is covered with a thin layer of mangrove leaf litter- and of course, that's part of the attraction here! This will not only provide an aesthetically interesting substrate- it will offer functional benefits as well- imparting minerals, trace elements, and organic acids to the water.

Mangrove leaf litter, like its freshwater counterpart, is the literal "base" for developing our brackish-water aquarium "food chain", from which microbial, fungal, and crustacean growth will benefit. And of course, these leaves will impart some tannins into the water, just as any of our other leaves will!

And you can play with many different types of substrate materials, ranging from sand to mud and everything in between. The richer the better, as far as I'm concerned. 

And of course, no brackish water aquarium is complete without brackish-water fishes...And traditionally, that has been a bit of a challenge, in terms of finding some  "different" fishes than we've previously associated with brackish aquariums. I think that this will continue to be a bit of a challenge, because some of the fishes that we want are still elusive in the hobby. New brackish-water fishes will become more readily available when the market demand is there. In the mean time, we can focus on some of the cool fishes from these habitats which are currently available to us.


However, one of the things I've found is that you need to go beyond "what the hobby articles say" and look into actual information from scientific sources about the types of habitats our target fishes actually come from. There is still a surprisingly large amount of misinformation about there concerning fishes long thought to be "brackish", when the reality is that they are often found predominantly in non-brackish habitats, with perhaps only isolated populations of fishes being brackish fishes.

And of course, the real "stars" of the show, IMHO, are those mangroves! Let's get back to them for just a few minutes...

Specifically, the "Red Mangrove", Rhizophora mangle. The one we'll focus on here and refer to as "Mangrove" for the purpose of this piece.

Hardly what you'd call an "aquarium plant"- I mean it's a tree.

That being said, the Mangrove is an amazing tree that certainly has applications for aquariums- specifically, brackish aquariums. Now, without going into a long, long, recap of what mangroves are and how they function (You can Google this stuff and get hundreds of hits with more information than you could ever want), let's just say that mangroves are a group of trees and shrubs which live in the coastal intertidal zone, in areas of warm, muddy, and salty conditions that would simply kill most plants.

They possess specialized organs which allow them to filter out sodium, absorb atmospheric air through their bark, and generally dominate their habitats because of these and other remarkable adaptations.

There are about 100-plus different species, all of which are found between tropical and subtropical  latitudes near the equator, as they are intolerant of cold temperatures. Mangroves put down extensive "prop roots" into the mud and silt in which they grow, giving them the appearance of "walking on water." These root tangles help them withstand the daily rising/falling tides, and slow the movement of the water, allowing sediments to settle out and build up the bottom contours of the local ecosystem.

And of course, the intricate root system not only protects coastlines from erosion, it plays host to a huge variety of organisms, from oysters to fungi to bacteria  to fishes. The fishes use mangrove habitats as a feeding ground, nursery area, and a place to shelter from predators.

Okay, you get it. But how do we use these trees in the aquarium. And wait a minute, you're talking about a tree? WTF?

I have no illusions about using live Mangrove plants (available as "propagules") to serve as "nutrient export" mechanisms as they do in nature. You've seen this touted in the hobby over the years, and it's kind of silly, if you ask me. They just grow too damn slow and achieve sizes far beyond anything we could ever hope to accommodate in our home aquarium displays as full-grown plants with large-scale nutrient export capabilities. We've played with this idea in saltwater tanks for decades and it's really more of a novelty than a legit impactful nutrient export mechanism.

Mangroves can and will, however, reach a couple of feet or so in an aquarium over a number of years, and they may be "pruned" to some extent to keep them at a "manageable" size, similar to a "bonsai" in some respects.

You've probably figured out by now that I'm a huge fan of mangroves!

Well, yeah. I am.

Oh, and before you part going off on me about their unsuitability for aquariums or some ethical implications for their "removal" from the wild, let's talk for a second about how we acquire them and how they grow. First off, removing a growing mangrove tree or seedling from the natural environment is damaging, unethical, illegal in most areas, and essentially idiotic.

NO one should even consider doing that. Period.

Rather, we acquire mangroves as propagules- buoyant seedlings which grow through the fruit, and can produce its own food through photosynthesis. When the propagules are mature, they fall into the water, and can remain in a dormant state, withstanding desiccation, for more than a year! Propagules are buoyant and can float until they find suitable "anchorage." When it's ready to take root, a propagule will change its internal density to float vertically, rather than horizontally, to make it more likely to root in suitable sediment. 

As aquarium people, we start with these free-floating propagules, which are abundant and legal to collect in places like Florida, where the adult plants are protected from harvest or pruning. They're often found washed up on beaches throughout their range. The advantage of propagules is that they can be stored in a moist environment and easily shipped in damp paper towel, and stored that way for extended periods.

So, once you have one of these pickle-like propagules, how do you use it?

First off, you don't need to "root" it, or "plant" it in substrate. You simply need to anchor it in the water column in a vertical position, and allow it to extend roots down towards the bottom on its own pace. I have typically done this in relatively small containers of water, like a jar, vase, or pitcher, before translating it to the aquarium. 

You'll know that the propagule is ready to transplant when it becomes a "seedling"- with little roots showing up on the bottom, and leaves beginning to unfurl on the top of the propagule. You can sprout the propagules in all sorts of light conditions- typically even room ambient lighting (as in a windowsill) will do the trick.

Fluorescent, LED, or other aquarium-rated "daylight" lighting will accomplish this, too. Of course, the part with the leaves needs be anchored above the water line (yeah, people ask me this question regularly). Like everything we do in the "natural-style" aquarium game, patience, diligence, and observation are essential when keeping Mangroves.

If using an artificial light source, be sure to mount the light well above the container or aquarium where the mangroves are kept. This not only results in a more natural-looking growth form- it keeps the leaves from growing literally right into the light and frying themselves (I've done that many times, lol).

Once they are placed in the aquarium, you should anchor them near the water surface, not in the substrate. As discussed many times before, I've chosen to attach my propagules to (legally-collected) mangrove root pieces in my brackish- water aquarium, and that works really well.

Allow the roots to "find' the bottom for themselves. This will encourage the growth of a strong, almost "woody" prop root system that these trees are famous for. It may take many months for them to achieve "touchdown and penetration" into the substrate, but they will- and a stronger plant ensues as a result of allowing them to do it themselves!

One little word of advice: Be sure to sprout your mangrove propagule in the same water conditions (ie; marine, brackish, fresh) as you will be keeping them in perpetuity in your aquarium. They categorically don't adapt well to habitat changes once they have begun to grow.

Of course, we need to go back to talking about substrates once more. Keep in mind they come from muddy, sedimented, nutrient-rich environments in Nature, so they can handle just about anything. I've personally utilized everything from marine biosediments to aragonitic sand, to mixes of pond soil or aquatic plant soils. You can mix in peat and all sort of substrate enhancement materials to provide sustenance and proper rooting for these hardy trees. A little online research can yield lots of great tips on substrate mixes for mangroves in the captive environment.

The beauty of mangroves is that they're pretty hardy and generally adaptable- which bodes well for their care in the aquarium! You need to do little more than illuminate them, anchor them in a vertical position above substrate, and mist the leaves on a regular basis. This process helps to keep dust, salt build-up (which is exported via the leaves), and insects off of the leaf tissues.

Now, again, we hear arguments that keeping a tree in an aquarium is kind of crazy.

I admit, a full-grown mangrove tree is virtually impossible to keep in a home aquarium. However, these trees grow incredibly slowly, reaching "houseplant-like" sizes after a year or more in captivity. And, with frequent pruning, you'll see that they can be maintained in almost a "bonsai-like" size indefinitely- all the while putting down the extensive, intricate  root systems that they are so famous for.

Yes, I'm repeating myself here, but . I really want to emphasize that point.

One of the cool benefits of mangroves in the aquarium- just as in Nature- is that their roots will recruit and foster the growth of microorganisms, fungi, algae, and other epiphytic life forms, providing a foraging place for fishes, and the ability to contribute to the biodiversity and healthy function of your aquarium ecology.

In addition, the "leaf drop" which mangroves are known for accomplishes the same thing it does in Nature, too! It encourages the growth of microorganisms and other life forms, and tinting the water via exudation of tannins and humic substances. As you might guess, I encourage the fallen leaves to accumulate and decompose in the aquarium! 

Yes, I'll point it out again, because I keep hearing this myth: I don't talk about utilizing mangroves as a "nutrient export" mechanism in your aquarium because it would take many mangroves (like, more than your tank could ever accommodate) over many years to provide any noticeable nutrient export effect on your tank. Rather, we choose to focus on their unique aesthetics and their ability to foster the growth of other, beneficial life forms.

Sure, we could probably go on and on about keeping mangroves in your aquarium (and probably will again I the future), but I hope that this admittedly superficial review will encourage you to research more about these remarkable trees- and try them in your aquarium. 

In summary, a newer, more evolved interpretation of brackish water aquariums is both fascinating and necessary to push this interesting hobby speciality forward, IMHO.

Traditionally, in the aquarium hobby, when you've mentioned that you're thinking of trying a brackish water aquarium, it's provoked little more than a raised eyebrow or a feigned level of interest from fellow fish geeks, and I kind of can see why. Although aquarists have been playing with brackish tanks for decades, in my opinion, what's been missing is a focus on the actual habitat we are interested in, and how it functions.

Functional. Yeah.

Just like what the hobby was doing in the blackwater area for years, I think we've been collectively focusing on the wrong part of the equation for a long time- just "salt" and basic aesthetics. And quite honestly, the hobby "knowledge base" on the wild brackish water habitats and how dynamic, interesting- and yeah, awesome-looking they are has been sadly lacking. 

Brackish water aquariums are a sort of "middle ground" that, for decades in the hobby has been well-travelled, yet widely mis-understood. I've played with brackish water for almost two decades, in between reef keeping and my blackwater stuff, and in researching both the hobby work that has been done, and relevant scientific papers out there on the wild habitats, have sort of made this conclusion that it's simply been an afterthought, at best for aquarists.

Although there is a good amount of information on brackish-water habitats from which brackish water fishes come, in the hobby, (with the rare exception of some biotope enthusiasts) we've sort of distilled brackish-water aquarium aesthetics down to white aragonite sand, a few rocks, and maybe some hardy plants...and it's been mired in that aesthetic hell for decades.

Time to change that. Time to push forward...

I'd like to think that our small efforts at sharing a different approach to brackish water aquariums has been inspirational and informative. Of course, I have no illusions about this being "the best way" to do brackish. This approach is a bit more challenging, demanding, and dynamic than those we have taken historically when working in this niche. However, I think that this more evolved, functionally-aesthetic approach is a better way for those who are up for the challenge and hungry to try something new.

So, as we say "sayonara" to our current brackish tank, we say hello to a potentially new and very exciting era in the history of this hobby specialty area.

Stay excited. Stay inspired. Stay experimental. Stay diligent. Stay bold...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

September 23, 2019


Keeping it real...

We're some four years into our existence here at Tannin Aquatics, and it's been amazing to see botanical-style aquariums starting to really catch on and become a definitive "movement" within the hobby. 

It seems that everywhere we turn, there is a growing interest in adding "twigs and nuts" to our aquariums, with more and more aquarists considering (and actually creating!) a botanical-style, blackwater aquarium. This idea, formerly a sort of "side show" novelty, is rapidly moving into the mainstream of aquarium technique, and lots of interesting developments are happening.

This is quite gratifying to me, as it's something I loved for a long time, with seemingly very few friends to share it with. In this instance, "scratching my own itch" to start Tannin certainly seems like it was a good idea! Now, the word "botanicals" is something we see quite a bit in the hobby. I'd be hard-pressed to have seen the term even used in the aquarium context prior to our debut in 2015. I've been told by some people that botanicals in aquariums are sort of a "trend."

Of course, whenever you see something becoming an emerging "trend" (Urghhh.. I HATE that word when used in the context of an aquarium topic!), you will see hobbyists making incorrect assumptions, having general misconceptions, and occasionally, unintentionally spreading wrong information about stuff. You know, regurgitating outdated or erroneous information that's been floating around out there on line for decades...

It's often a function of the fact that some of this stuff has been either under-utilized, completely misunderstood, or simply not appreciated for so long, that we've simply not really considered the dynamics involved in this context. 

Totally understandable, really.

And of course, being one of the leading proponents (and arguably, one of the more visible and one of the freaking LOUDEST) of this type of aquarium keeping, we have an obligation to the hobby community to provide correct information and clarification whenever possible, and to advise when we think something that's bandied about might be incorrect. And, when assumptions are becoming "fact" in our discussions, we do need to address them in our discussions from time to time.

Of course, one of the best ways to "keep it real" and address this kind of stuff is tell it like it is!

And it all starts with getting one thing straight right from the start...

As we have said like 140,000 times already, no one "invented" the idea of using botanicals in aquariums- least of all, us. However, we have made it our mission to educate, elevate and innovate in this world, so let's get to it!

Here are a few topics that we've seen discussed from time to time which, in my opinion, need to be clarified and thought through a bit before making conclusions. Obviously there are like 10,000 other more topics out there, and we could probably write a column on each one of these! (and we just might over time, right?)

So, here's a start; the beginning of a dialogue which might provide some clarity on some important aspects of the blackwater, botanical-style aquarium:

1) Botanicals cannot soften hard water. This is one of the more persistent misconceptions floating around. It started decades ago, with hobbyists thinking that leaves could do it, and it's continued right up until the present. Now, it's been proferred by some that materials such as peat moss can act to some extent as  a sort of "ion exchange resin", removing some minerals from the water and replacing them with humic acids, and perhaps this is where the idea that "all botanicals" can influence water chemistry accordingly arises. Botanical items (leaves, wood, seed pods, cones, etc.) do contain tannins and humic substances, and if used in sufficient quantities, can certainly lower the pH somewhat in water which is low in carbonate hardness.

However, these botanicals themselves simply cannot lower the hardness of your water. That needs to be accomplished by a process of ion exchange (such as reverse osmosis/deionization). If you start with hard, alkaline source water (which contains lots of dissolved minerals), and toss in some leaves or seed pods, or whatever, the botanicals will essentially do nothing to remove them.

"Soft" water is water that contains low levels of dissolved minerals, and as such, has lower ability to absorb acid substances, which will accumulate and lower the pH. That's why the effectiveness of botanicals in lowering pH can be significant in soft water. We've addressed this before, and you can find lots of articles on water chemistry on line.


2) Don't let the tint fool you. Remember, the visual color change imparted to the water via the aforementioned tannins is not an indication that you have soft, acidic water. In the absence of chemical filtration media such as activated carbon, which remove coloring agents from the water, the tint will be most evident as these materials enter the water.

However, don't forget that you can still have very hard, alkaline water and have some color. Just look at your municipality's annual water report...they actually mention visual tint" in their assays. So I guess one could call tint a "vanity metric" (to steal a marketing term) in our world, that it's really an observation of "cosmetic appearance" versus a manifestation of functionality (ie; lower pH and hardness).


3) There is no "recipe" for how many botanical materials will accomplish a given affect within your aquarium water. Yeah, we've mentioned this dozens of times, and it warrants repeating. Although I can make crude estimates based on personal experiences with regard to how many leaves (for example) it took to lower my pH from ___ to ___ in water with little to no general hardness, it's both unrealistic and misleading for me or anyone to suggest that adding specific numbers of various botanicals to your tank can give you a specific effect.

If for no other reason than the fact there are countless variables in everyone's aquarium and water, and that the botanicals themselves, being natural materials, may have varying levels of pH-affecting tannins and such in a given sized leaf (as one example), we just can't quantify this. We might tell you to start with "x" number, just because I do- but it's not a "recipe", okay? You need to start off with what seems to be a reasonable number of materials and test your water regularly to determine the impact on your aquarium. It's still about nuance, exploration, and experimentation.

All changes need to be done slowly and carefully.


4) The creation of food webs is interesting, but is not spontaneous or even a "given" when utilizing botanical materials in your tank. Sure, we spend a lot of time talking about the concept of creating a system which facilitates the growth of significant quantities of organisms (such as microorganisms, fungi, small crustaceans, worms, and aquatic insects), but the reality is that just throwing  leaves and seed pods into your aquarium isn't the whole story.

Sure, as they decompose, they'll fuel some microbial growth, and generate biofilms and fungi. However, you'd likely need to "inoculate" your system with small crustaceans like Daphnia, Cyclops, Gammarus, etc. in order to have more complex and diverse food sources available to your fishes. And you'd need to do this prior to adding fishes (which will consume them rapidly!), or in the confines of a separate "refugium" installed solely for the purpose of cultivating these life forms. It's an interesting, and potentially game changing idea- particularly for fry rearing systems...

5) Botanicals will not give your aquarium a permanent, stable hardscape! Nope, by their very nature, these materials begin to break down as soon as they hit the water, so the "clock is ticking" as they say! Now, some materials (the more durable seed pods, etc.) will last longer than say, leaves, which break down in a matter of weeks. However, the vast majority of botanicals all begin to decompose and physically change appearance over time. And this is a cool thing, really...this is exactly what happens in nature. These materials create what could best be referred to as an "ephemeral" hardscape. One which might well be anchored by permanent pieces like rocks and driftwood, but is accented by the changing condition of the botanicals.

We like to refer to this as an "evolving" aquascape, and I think that's a pretty accurate descriptor. And it reflects both the charm and attraction of the blackwater, botanical-style aquarium. Unlike many "traditional" aquascaping approaches, a significant part of the appearance of the tank is driven almost solely by nature, and as such, will change as materials break down, are moved about, and/or covered with biofilms and algae.

This is exactly what happens in the wild, and is why we say that operating this type of aquarium requires a distinct "mental shift!" Now, you can of course, keep your aquascape looking pretty close to the way it started out if you regularly remove, clean, or replace the botanicals. However, this level of "intervention" may not appeal to everyone!


6) Botanical-style aquariums are not "set and forget" systems.  I mean, no aquarium really is. However, in the case of a botanical-style aquarium, it's pretty much a non-starter! Look, you're talking about a tank with (typically) soft, acidic water, a fish population, and a large quantity of materials which are breaking down steadily. This number of critical variables requires regular observation and management on the part of you, the aquarist.

I would not state categorically that these aquariums are teetering on the brink of disaster at all times. I personally have never had a "crash", or have seen rapidly rising, out-of-control nitrate levels in an actively managed blackwater, botanical-style aquarium. Like any type of aquarium, you need to observe, monitor, maintain, and track your aquarium's status as it evolves. You'll learn to spot emerging "trends" which may or may not prove problematic to your specific system. Sure, you don't need to apply the same high level of diligence that you might with say, a coral propagation system or Discus breeding tank, but the simple reality here is that you're going to have to get your hands wet.

7) Patience and the passage of time are the key ingredients. Over time, botanical-style tanks seem to reach a sort of "equilibrium", where you won't see significant parameter swings or changes. The bacterial population adjusts to the amount of materials in the tank, provided you don't continuously add large amounts stuff, overfeed, add large quantities of fishes, or make sudden, abrupt changes in procedure. Consistent practices always work best. 

These tanks are no more inherently unstable or "dangerous" (something we've heard in the past about blackwater/botanical-style tanks) than any other system. You just need to understand the dynamic, including things like biofilms, decomposition, and detritus, which might have scared the shit out of you in the past- as part of the "normal" for these aquariums. You simply need to embrace and accept the limitations of a given tank, and to not expect to simply "sit back, relax, and enjoy the flight" as they say. Don't expect sudden shifts for the better or the worst.

Stay consistent, involved, observant, and above all- patient- and you'll be just fine. 


Sure, I could probably go on and on and cover all sorts of different, rather arcane topics and "myths" within this context, but I think we've addressed the most important- and common ones- that we see discussed. And hopefully, this provides a contextual framework for you to explore and discuss more about the design, construction, and management of botanical-style blackwater aquariums. 

It's an exciting, evolving area of the hobby, breaking out of the shadows of misconception and obscurity. We need to get better and better at sharing actual experiences with this stuff, rather than simply "regurgitating" second-hand information, as is so common in the hobby these days. And, like everything else, this type of evolution takes time. It takes patience. It takes understanding...and lots of sharing of firsthand information.

Are you up for it?

Stay engaged. Stay involved. Stay methodical. Stay excited. Stay curious...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

September 22, 2019


Setting the stage...

As I muse the idea of several new aquascapes over the next several weeks, as part of an "Autumn refresh" I'm hell-bent on doing, I can't help but think back on the ideas I've played with in the past; particularly those which started out a certain way and ultimately evolved into something quite different.

And of course, one of the best things about starting up all of these new (blackwater) botanical-style systems is that I get to go through the full experience yet again, and look at things a bit differently- a bit more closely and intimately than I would if I were a bit more detached...

I realized, early on in my "serious" aquarium affliction, that I take a sort of different view than a lot of hobbyists and aquascapers about setting up aquariums. I can barely set up a tank which looks "finished" from day one. Like, you know how the really talented 'scapers can set up a tank with all of the wood and plants and such in place, and the tank looks "done?" I just can't do that. Sure, once in a while, I might nail the hardscape- but for the most part, my tanks are just beginning after the "work" is done.

They look a bit sterile; almost too artificially contrived at that point. I've sort of learned to look beyond that time frame, and realize that all that I've really done is sort of set the stage for the "evolution" to come. In summary- my tanks almost always look like shit at the outset.

Yeah, they need time.

I set tanks up for the long run. 

Like, I cringe a bit when clubs will ask me to set up a "blackwater aquascape" at a meeting. I'm usually horrified, because the tank will literally look like a pile of leaves and botanicals and such when I[m done with my 45 minute "scape", and it's completely out of context with my "world view."

My game is just beginning when the last leaf is dropped...

I'm fascinated by what happens at what, to me, is arguably one of the more fascinating times in developing this type of system: That period when the essential "anchor" hardscape is done. The largest wood pieces are set. The tank has that sterile-looking, stark appearance that leaves no doubt about this being artificial at this stage.

If we go back to one of my all-time-fave blackwater aquariums from about two years ago, I remember being at this stage and the look that could only be referred to as a "campfire-style" wood stack, which certainly gave off that "contrived" or "not-fully-fleshed-out-idea" vibe. And that, of course, generated concern, questions and suggestions from my more talented friends to make the layout of the wood look more "artistic..."

Feedback which, in years past, would put a lot of doubts in my head.

Not in the last decade or so, however. 

As with a lot of my recent tanks, I had a vision for that one. A game plan...And I had patience to let it unfold gradually, steadily. I knew that the wood had to be in that sort of configuration, seemingly artificial though it may seem early on, because the picture I had in my head dictated that.

It's this idea of "setting the stage" for the long term that engages me in aquascaping. I think it's a mindset and way of looking at things which can really set our work as botanical-style aquarium lovers apart from virtually everything else out there. 

We scape for the future. Literally.

Going back to the example from a couple of years back- it simply followed this philosophy to a "t." This aggregation appeared to be more like a bunch of branches placed in the woods for the purposes of making a fire at some future date than some "high-concept" hardscape....


OR, could it be representative of the way a tangle of branches might slowly assemble itself, given a unidirectional flow of an inundation caused by an overflowing stream?


The pic below by David Sobry gives me some interesting ideas...and context.

Oh, interesting...

Yeah, I've found that some of the most compelling aquascapes- botanical-style, hardscape, planted, reef, etc.- seem to have a special "something" about them. Of course, a large part of it is the overall "look"; however, one of the things which, in my opinion, separates good tanks from great ones is the little details...stuff that completes the underwater scene.

Not necessarily "structural" details, like anchor hardscape pieces, mind you. No, we're talking about little, subtle details which make a system more natural-looking and "shade in the corners" where needed. Leaves, twigs, and smaller seed pods. The big pieces, which, in ANY scape, seem to be "harsh" and "sterile" when first laid down, take on a softer, more "realistic" vibe after they acquire that patina of biofilms and such weeks later.

And, those little things do make a difference over time.

For example, in our botanical-style world, it's little things, like bits and pieces of broken up botanical materials, like bark, twigs, the occasional larger seed pod or what not, which make your scene look much more complete and lively.

If you take your cues from natural underwater habitats, like I do, you'll notice that they are filled with all sorts of materials- not just the more obvious leaves and branches. If you think contextually, particularly when we're talking about habitats like igapo inundated forests and igarapes ("canoe ways" in the Amazonian forests), take into account that they literally are flooded forest floors.

As such, they have seemingly random aggregations of botanical materials scattered about everywhere, punctuated- or, rather defined- by larger features like fallen logs, branches, a few random terrestrial plants poking through.

The look of sort of awkwardly-placed hardscape pieces in an aquarium might certainly not be seen as being "artistic", in the way fabulous work by my friends like Jeff Senske at Aquarium Design Group are- but, in my opinion, it's nonetheless compelling- once the details arrive to soften and fill in the scene.

See, I said the "D" word.


I believe that an aquarium that attempts to replicate a sort of chaotic scene like the ones we're talking about starts with what looks like really artificial placement of wood, anchored by numerous details which soften, define, and fill in the scape. A sort of analog to the theater/motion picture concept  of "mise en scene", where pieces literally "set the stage" and help tell a story by providing context.

Yes, unlike a scape which depends upon growth of plants to fill it in and "evolve" it, the botanical-style blackwater aquarium is largely hardscape materials, which requires the adept placement of said materials to help fill in the scene. And of course, part of the "evolution" is the softening, redistribution, and break down of botanical materials over time...just like what happens in nature.

(One of Mike Tucc's underwater igarape pics to the rescue..again!)

I suppose this little rant could be viewed as a "defense" of my philosophy, lol!

Perhaps it is.

But I think it serves to re-examine what I feel is one of the foundational philosophies of the botanical-style aquarium aesthetic:

The passage of time.

The ability to get out of our own way and allow things to evolve naturally. A sort of "hands-off" approach. Like, one of my friends asked me about my approach to 'scaping these tanks, "It's like you set the tank up and just don't even look at it for a few weeks, right?"

Well, sort of. Yeah! 

I mean, not literally, but I don't typically look at them and start editing like mad, unless I have a burst of inspiration that requires me to make some sort of fundamental change before the tank gets too far down the path of "evolving."

I must confess, it's an aesthetic and an approach which certainly doesn't appeal to everyone. It defies current thinking and challenges us to cede some of the work and control to Nature. To accept aspects of an aesthetic which make us face some fears that we might have had for many years...

In fact, many in the mainstream aquascaping world would levy all sorts of "constructive criticisms" and "Yeah, but..." comments about our practices and ideas..

And that, to me- is part of the attraction of this type of aquarium. Rather than conform thoroughly to some sort of "rules" based on design, layout, and technique, this type of aquarium tends to ask for very basic initial design, and lets Nature handle a lot of the emerging details over time.

That's really f---king hard for many aquarists to do.

I get it.

However, you need to have some faith in Nature and her work...

She's damn good at it.

And, you need to learn to embrace the subtle beauty of things in Nature that you might not have initially found even remotely attractive or alluring...

Rather than just looking at wild aquatic habitats and telling yourself, "Gee, that's nice, but..."- try accepting Nature's challenge and try to recreate it in your aquarium- both functionally AND aesthetically. Learn to embrace and see beauty in natural features that might make you uncomfortable, rather than attempting to "edit" or "polish out" what many consider "undesireable."

This is a slightly different approach to aquascaping than we usually think about. It requires some longer-term vision. To see beyond the "first hours" of the tank's existence. It requires belief in one's ideas. It requires a different sort of understanding about what we're doing here...And it requires patience above all else.

And the passage of time.

Nature has been working with terrestrial materials in aquatic habitats for eons.

And nature works with just about everything you throw at her.

She'll take that seemingly "unsexy" piece of wood or rock or bunch of dried leaves, and, given the passage of time, the action of gravity and water movement, and the work of bacteria, fungi, and algae- will mold, shape, evolve them into unique and compelling pieces, as amazing as anything we could ever hope to do...

If we give her the chance. 

If we allow ourselves to look at her work in context.

And, if we set the stage.

That's it for now. I have to tend to another "campfire..."  I"m working with on a new tank.

Stay thoughtful. Stay determined. Stay diligent. Stay faithful. Stay independent. Stay bold...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



September 21, 2019


A most intimate relationship

The relationship between land and water is something we talk about quite a bit here. And I think it deserves mentioning more often- and occasionally, examining in greater detail. 

With blackwater systems, there is a unique set of environmental relationships which create and  maintain these habitats and their chemical/physical/ecological makeup. And it starts, of course, with water! 

We've often mused in the hobby about what pH is “appropriate” for blackwater aquariums, and it’s really hard to pin down one number.  The reality is that many natural blackwater systems are far more acidic than we could ever hope to achieve in our tanks. Where does this acidity come from?

Recent studies found that most of the acidity in black waters can be attributed to dissolved organic substances, and not to dissolved carbonic acid. In other words, organic acids from compounds found in soil and decomposing plant material, as opposed to inorganic sources. Blackwaters are almost always characterized by high percentages of organic acids.

Interestingly, however, these waters are surprisingly low in dissolved organic compounds (DOC). In fact, Rio Negro black waters are theorized to have low DOC concentrations because of thdiluting effect of significant amounts of rainfall, and because they are diluted by clear waters from nearby systems low in dissolved organic compounds.

Sort of  “self-regulating”, to an extent, right?

In the podzol soil where black water originates, most of the of the extractable substances in the surface litter layer are humic acids, typically coming from decaying plant material. Scientists have concluded that greater input of plant litter leads to greater input of humic substances into ground water.

In other words, those leaves that accumulate on the substrate are putting out significant amounts of humic acids, as we've talked about previously! And although humic substances, like fulvic acid, are found in both blackwater and clear water habitats, the organic detritus (you know, from leaves and such) in blackwater contains more extractable fulvic acid than in clearwater habitats, as one might suspect!

The Rio Negro, for example, contains mostly humic acids, indicating that suspended sediment selectively adsorbs humic acids from black water.  The low concentration of suspended sediments in rivers like the Rio Negro is one of the main reasons why high concentrations of humic acids are maintained.

With little to no suspended sediment, there is no "adsorbent surface" (other than the substrate of the river, upon which these acids can be taken hold of (adsorb).

When you think about it, all of this this kind of contributes to why blackwater has the color that it does, too. Blackwater in the Amazon basin is colored reddish-brown. Why? Well, it has  those organic compounds dissolved in it, of course. And most light absorbtion is in the blue region of the spectrum, and the water is almost transparent to red light, which explains the “red” coloration of the water!

And many of those organic compounds come from the surrounding land, as touched on above...

The relationship between terrestrial habitats and the aquatic environment is becoming increasingly apparent in these areas. 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.

Fishes depend upon the fruits, seeds, insects, and other materials which come from the surrounding terrestrial habitat for food. When these areas become seasonally inundated, more food sources are available to the fishes which reside in these habitats. So, it kind of goes without saying that preservation of the forests themselves is really important for the fishes! If you take away the forest, you take away the fishes, too! 

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 various 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.

Shortly after falling into the water, fungi and other microorganisms act to colonize the surfaces, and biofilms populate the bark and exposed surfaces of the tree.  Over time, the tree will impart many chemical substances, (humic acids, tannins, sugars, etc.) into the water.

The  fallen tree literally brings new life to the waters.

The materials that comprise the tree are known in ecology as "allochthonous material"-  something imported into an ecosystem from outside of it.  (extra points if you can pronounce the word on the first try...) And of course, in the case of fallen trees, this includes includes leaves, fruits and seed pods that fall or are washed into the water along with the branches and trunks that topple into the stream.  

These materials are known as “coarse particulate organic matter”, and in the waters of these inundated forest floors there is a lot of CPOM, and the community of aquatic organisms (typically the aforementioned aquatic insects and crustaceans) has a high proportion of “shredders”, which feed on the CPOM and break it up into tinier bits called (wait for it) "fine particulate organic matter" (FPOM).

And of course, some fishes, like larger characins, catfishes, etc., consume fallen fruits and seeds as part of their diet as well, aiding in the "refinement" of the CPOM. Other organisms make use of the fine particulate matter by filtering it from the water or accessing it in the sediments that result. These allochthonous materials support a diverse food chain that's almost entirely based on our old friend, detritus!

Yeah, that detritus.

The stuff of nightmares for many dyed-in-the-wool hobbyists...the stuff of dreams for many fishes who consume it and the associates fauna within it.

And, although the forest floor receives substantially less sunlight than open rivers, the nutrients and available light are utilized by algae, which may colonize the surfaces facing up into the sun. 

We see similar results in our aquariums, right?

And of course, the tree, like almost anything that is submerged,  will gradually decompose over long periods of time. This process is actively exploited by aquatic life forms at all levels. Hollowed-out sections will be inhabited by fishes and exploited for the shelter they offer, and of course, the aforementioned crustaceans and insects will utilize the tree in various ways.

And interestingly, when you think about it, fish movement and species richness and population is directly affected by the physical and biological influences of... fallen trees! And the deep beds of leaves that may be "corralled" by the fallen trees- a sort of natural "dam"- will definitely limit some fish species, which cannot tolerate the lower oxygen concentrations found in these areas.

Other fishes take advantage of the "physical barrier" that a fallen tree presents to shelter from predatory species. Many adaptations have taken place over eons to allow fishes to exploit these changes to their environment caused by fallen trees!

It's pretty hardcore stuff. And pretty fascinating.

Like so many things in nature, the complexity of blackwater habitats is more than what meets the eye. Chemically, biologically, and ecologically, blackwater habitats are a weave of interdependencies- with soil, water, and surrounding forest all functioning together to influence the lives of the fishes which reside within them.

No single factor could provide all of the necessary components for fish populations to thrive. To damage or destroy any one of them could spell disaster for the fishes- and the ecosystem which supports them. It is therefore incumbent upon us to understand, protect, and cherish these precious habitats, for the benefit of future generations. 

It's not only vital for us to understand how these habitats work in nature- it's important for us to be able to replicate some of its functions if we want to be able to keep and breed the fishes that we keep which hail from these habitats.

It truly IS a most intimate relationship.

Stay studious. Stay diligent. Stay observant. Stay curious...And Stay Wet.


Scott Fellman

Tannin Aquatics 

September 20, 2019


Yeah, I killed it.

I think that I use this blog as a sort of "therapy session" sometimes.

You guys are like a "sounding board" for me!

And sometimes, I have "issues" that I just need to look at and share to get over them, lol.

You have to address your fears. Share your successes, failures, struggles, and challenges.

Okay, maybe you can relate to this one.

Maybe not, but...

So, you have this idea for an aquarium. You kind of see it in your've assembled the materials, got it sort of together.

You add water.

Then, you walk in the room one day, look at it and- you HATE it.

Like, you're done with it.  Like, no re-hab on the design. No "tweaking" of the wood or whatever...You're just over the thing. Ever felt that?

What do you do? 

Well, I had this idea for a nano tank last week. It seemed good in my head...I had it up for a nanosecond.

Even memorialized it with some Instagram Stories posts.

I thought that the tank would be a sort of "blank canvas" for an idea I had...I liked the idea, in principle.

But I didn't see a way forward with this one. I even took the extraordinary step of removing one element of the tank (the wood) altogether, in the hope of perhaps just doing my "leaf only scape V3.0"- but I wasn't feeling it.


A stillborn idea. A tank not capable of evolving to anything that interested me at this time.

So...I killed it.

Yeah, made away with it. Shut it down. Terminated it...

Whatever you want to call it.

That's really a kind of extraordinary step for me. I mean, I'm sort of the eternal optimist. I try to make almost everything work if I can...

Not this time, however.

I killed it.

Now, in the hours after the aborted aquarium move, I'm actually able to gain some clarity about why I did it.

What made me do it? 

I think it centered around two things that I simply can't handle in aquariums anymore.

Don't laugh:

1) I absolutely can't stand aquariums which don't have some sort of background- be it opaque window tint, photo paper, or paint. This tank had no background. You could see the window behind it, and the trees outside on the street, and...yeah. 

2) I disdain seeing filters or other equipment in my aquariums. Like, I hate it more than you can ever even imagine.  Like, I hate seeing filters and stuff. Its only in recent years that I've been able to tolerate seeing filter returns in my all-in-one tanks...and just barely. Now, this nano had a little hang-on-the-back outside power filter...Which I not only saw from the top, but from behind...because-you got it- I didn't have a goddam background on the tank, yes.

I mean, am I that much of a primadonna that I can't handle that? I mean, maybe, but I like to think of it as a situation where I have simply developed an aesthetic sense that just can't tolerate some stuff anymore. I have good ideas, and then I get to equipment...and it sort of "stifles" them a bit.

This is weird.

Okay, yeah, maybe I am prima donna.

What could I have done to salvage this tank?

Use a canister filter and glassware, you say?  

Oh, sure. That's easy, right? I mean, all you see in the tank are these elegant curves of "lily pipes" and intakes...You just take 'em out and bleach 'em every once in a while and they stay nice and clean, and.. Okay, yeah. Great. On paper, anyways.

IMHO, glassware isn't the "organic art" that everyone seems to place on some lofty pedestal in the hobby. It reminds me of high school chemistry lab (which I think I got a C minus in, so some residual trauma there, no doubt). You think it's beautiful...I think it's simply dreadful.

It's another piece of equipment, which you see on the outside of the tank, too, with its "umbilical" of return lines shooting up along the sides. Now sure, I know these were developed to make an obvious, visible necessity (filter returns) more elegant and beautiful...However, to me, they're just that- obvious, visible, distracting...and ugly.

I know, I'm being too stupid about this. 

Lest you think I'm simply not experienced enough with this concept, or just not able to see the "big picture"- I can prove to you that I have flirted with this stuff before...

Yep, I wasn't always like this.

When I did a stint at a very high-end aquarium design firm in Greenwich Connecticut a few years back, I was intimately involved in the creation of a significant artistic aquarium project in the lobby of an iconic New York City office building in the heart of Park Avenue- seen by tens of thousands of people daily. A reef aquarium in an insanely cool customized acrylic sculpture.

It was done in consultation with artist Paula Hayes, who envisioned the project as a sort of demonstration of the dependency between land and water- in a very artistic, perhaps slightly abstract, yet undeniably interesting manner.

And yeah, we had to incorporate life support systems and "umbilicals" for the filter returns and intakes...that was literally the whole point of the installation. We had to embrace that stuff. I had to get over myself and decades of reef aquarium snobbery in order to help do my part with a talented crew to bring this project to life.

And we did bring it to life.

And it was beautiful.

And it was impactful, too-seen by literally tens of thousands of people everyday. Connecting them to the aquatic world- which many had never even seen or experienced before...And guess what? Not a single person ever complained, or even asked about the "umbilicals" extending out of the tank.


They were enamored by the fishes and corals.

Like, it's only me.  

I imagine that no one I know is as weird about this stuff as I am.

And look, I'll be the first to admit that even my "beloved" all-in-one-tanks, although a bit of an improvement, still aren't "the last word" on visible equipment. There a sort of "band aid" for my psychosis, I guess.

As a reefer, you learn to hide a lot of equipment, and you use whatever means you can. And all-in-one tanks aren't really held in high regard in the reef world, ironically.

However, they work for me in many cases in this freshwater game..

They're a start...

At least a way to sort of circumvent my apparent "psychosis" on this thing. I mean, you still see the return. You see an overflow weir...Of course, you have colored background. I can't say I LOVE black backgrounds. However, you don't have tubes and shit running up the side of the tank...

Maybe just a power cord or two...but hey...

The all-in-ones are limiting, I agree. They're not a "cure-all", of course. A lot of people simply despise them for many reasons. They're not perfect for overcoming every aesthetic issue.

There are some things I don't like about them, sure. 

You're stuck with the dimensions that manufacturers make available. You're limited to the way they configure filter compartments, by the interior depth (reduced because of the filter compartment), etc.

However, they can produce tanks which don't have all of that visible crap in the tank. Maybe they're a gentle way for me to get over my "thing." I only can hope that one day, an aquarium manufacturer consults me next time they want to bring an all-in-one to market!

I think I have a few ideas...hint, hint...

Now, look- getting back to my recent aborted tank, I think it was a case of "I had good idea, but couldn't get over the things that drove me crazy". In fact, the problems were likely easily solved.

I could have simply applied some opaque backing to the tank- I wouldn't see the bulk of the damn filter.  I've done it before and it works just fine.

And glassware? Well, I HAVE used it before...It's something that I hate, but it DOES work great in many applications. Like, shallow tanks...

Hey, it's not that bad...yeah...

So, maybe there IS some sort of compromise. Some way for me to overcome this phobia of sorts...


I mean, the fact that 95% of the aquascaping world uses glassware and external filters- and overcomes this "aesthetic handicap" (okay, that's what I call it...) and embrace this stuff to create extraordinary aquariums should tell you something, right?


Yeah...maybe it's just me.

Well, I mean- it COULD be that they hate that stuff too, but haven't been as vocal about it as I am! Maybe they're afraid to rock the boat!  Yeah? Maybe?

Or, maybe they have figured out how to deal with this stuff?  Perhaps they're more practical than I am, and simply able to cope with challenges better than me.


Damn, I don't know. I think I need to lighten up a bit.

I killed this tank.

And I'm sort of glad that I did. It gave me a chance to discuss this. To deal with my "phobia" about some stuff...To get it off of my chest, and to once again focus on more important stuff...

Regardless of what kind of tank I keep things in.

Yeah, I killed it. 

Maybe this will be the last time...


I think I'm going to purchase some glassware today...

Hey, Thanks! 

You guys are great!

Stay helpful. Stay thoughtful. Stay engaged. Stay creative. Stay relaxed...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

September 19, 2019


The Nature of...Nature in our aquariums!

At least a couple of times a month, I'll get hit up on DM or somewhere by a fellow fish geek, asking what I think about how we define a "natural aquarium" or similar labels related to representing natural habitats in our aquariums. Now, this is an interesting- even devisive- topic in discussion forums and FB groups and such, because it seems to bring out everyone's passions.

Like, on one hand, there is a group of people who will tell you that it's simply "folly" to consider anything we do in a glass box "natural"- as they will assert that any functions that occur in an aquarium- from the nitrogen cycle on up to how plants grow- is not "truly natural..." Yeah, I had someone actually tell me that. With a lot of passion, no less...

And it made me think about it, for sure. 

I'm no scientist, but I'm not exactly sure how the nitrogen cycle, in its most basic function, differs in the closed environment of the aquarium from that in Nature. I mean, I suppose the factors which influence it might be different- such as a fixed population of fishes in a given space, versus a "wider ranging" natural habitat with a varying population density- but that seems a bit of a stretch to me...So yeah, I think that's a sort of weird argument...


Recently, I had a discussion with another hobbyist who asked me where I feel my personal and business work falls in the grand scheme of creating "natural" aquariums. It gave me some pause, because I think that we might get too caught up in labeling everything rather than looking at what we do in "the big picture" of the aquarium hobby. With my focus on "functional aesthetics" over almost anything else in this context, it definitely defines me as a bit of an outlier...

And of course, once you resolve the whole "natural" thing, you get to an even more passionate topic:

What constitutes an aquarium that represents a part of nature?

It can just get uglier from there sometimes...

I mean, it's a discussion that I think is worth having, for sure, if for no other reason than for us to come to some sort of a self-awareness about what we're doing. That being said, we can often create a "word salad" of descriptors that may simply be lots of ways of saying the same thing. Yes, I admit that I do cringe on occasion when the description "Nature Aquarium" is given to a tank which, although amazing, has little to do with a specific representation of a natural habitat.

Or, does it?

I think we can literally parse the living shit out of that term, and in the end, we'll end up right back where we started- with 50 different hobbyists arriving at 50 different definitions! I mean, most aquariums DO embrace natural processes and elements, so that keeps this in the mix.

The weird thing- or the GOOD thing, depending upon how you look at stuff- is that we in the hobby really stress out over this stuff; words matter- and people take it really seriously! We do tend to "self-regulate" our hobby, which is good in some areas, and downright annoying in others, right?

When we plan our aquariums, I know that many of us are super disciplined, highly detail-oriented, and attack the "fish list" with diligence and a high degree of "mission focus." Like, every fish added to the tank has to be from the general region that all of the others are from...or that the tank's 'scape is supposed to "represent."

I have always been focused like that- almost to the point of having tanks run empty for months at a time when I couldn't source the specific fishes I wanted...("Yes, Poecilocharax weitzmani IS the ONLY Darter Characin I shall have!") I can be THAT focused! Like, absurdly, impractically focused.

And, I must confess:

I'm not immune to any "temptations" I might encounter along the way to my ultimate goal...

There is always that part of me which falls headlong into that "shiny object syndrome"- you know, something cool catches my eye along the way, and there I am, off on a tangent, researching and considering ways to "modify" my plan...complete with justification ("Well, you know, just because I SAID it's going to be an Asian blackwater stream with Rasbora espie doesn't mean that I can't have a few of those Copella arnoldi in there. I mean, "SPLASHING-FREAKING TETRA- HELLO!")

(Image by Zikamoi, used under CC-BY S.A. 3.0)

Yeah, sad shit like that.

Of course, that's how the classic "community tank", which we've loved for generations, is created, right? The best combination of cool fishes, regardless of origin, which happen to catch our fancy. As long as they are physically compatible, does it really matter? I mean, what's wrong with that, right? 

Really, does every salad we make have ingredients from the same farm to be called a "salad?"

Weak or not, it is that kind of "argument" that would make ME feel better, lol.


I've always felt that inserting the words "themed", "inspired", "type" or "style" after the description of your aquarium gives you a bit of a "let", so to speak. In other words, my home aquarium is a "Southeast Asian-themed", which is far different than a true "biotope" aquarium, which, in hobby parlance, seems to have several classifications. 

Most of these center around the aquarium representation of a very specific niche or locale in Nature, with the requirements being to include organisms that are representative of the specific niche or region....or species, geographic locale, or- what they call in the contest world, an "ecological" aquarium.

I do kind of like that one.

Our friends in the Biotope Aquarium Design contest define an "ecological" aquarium as one in which "...aquatic organisms are selected by similar requirements to environmental conditions, without binding to a certain area or a biotope. For example, an aquarium for the fishes preferring cold water and strong current, or the fishes who need stone shelters and increased content of salts of total and carbonate hardness."

Okay, I can dig that. From my standpoint, it gives you as a hobbyist a lot of creative leeway.

Some space to create a nice representation without getting too bogged down in the minutiae of what twig or leaf is endemic to the region that you're representing. You can feel free to be a bit "creative", while still bringing the "flavor" of a specific niche or locale. 

Therefore, my "Southeast Asian-Themed" tank, or "Brackish Water Mangal-Inspired" system gives me the "permission" to keep together fishes which, although compatible, would likely never co-habitatate in nature. I get the "vibe" I want, create environmental conditions appropriate for each of the fishes that I want to keep, and just enjoy it.

Okay, did I just say "permission?" Yeah, I think I did...and that's sort of bizarre, too. Is there some "international hobby regulating committee" that I need "approval" from here? It's like I'm buying into that warped mindset...drinking the proverbial "Kool-ade" that the hobby is serving up.

Damn, WTF, right? That's a whole separate issue for another time, I think.

And my aquarium?

Well, sure, it's NOT a strict, biotopically exact representation of a mangal "in the Sarawak region of Borneo during the Spring", or something as specific as that. Nope. Rather, it's about creating an aquarium which is more-or-less "representative" of the broad environmental niches found in a given region.

I do like that.

And you can't really discount the fact that when you're researching the environment, the parameters, and the organisms which reside in given habitat when assembling our systems, regardless of how we approach them or what label we apply to them, we are still acquiring valuable information that can benefit many others in the hobby.

So, it doesn't matter if you take a very strict, almost militant approach to creating an aquarium, or more of an artistic, creative approach...The benefits for the hobby, the animals, and the natural environment are essentially the same. It still inspires; gets people thinking and talking.

I mean, in the end, it's all about having fun.

And it's about educating ourselves and others about locations, animals, and habitats that they may never get a chance to visit in person- and to bring attention to and discussion about the risks and perils they face as man continues to encroach on them.

That's huge.

Now, couldn't we make an argument that virtually any aquarium checks some of those boxes?


I mean, how much "detail" we want go into is a big factor. One could mix tropical fishes as diverse as Guppies, Tetras, and Dwarf cichlids and, I suppose, make some sort of stretch that they are "all from tropical locales" and therefore "represent" a "tropical environment." We've more-or-less done that with the traditional "community aquarium" for generations.

And that's okay.

Now, we can't fool ourselves, of course, if we are playing with such nomenclature. This type of aquarium represents Nature in the same manner as a vase full of flowers represents the fields in which they grow wild. But hey, I suppose it's a start...

Where am I going with this?

I suppose that I'm simply contributing to the clutter, disagreement, and confusion on the subject to some extent.

Well, in some areas, at least.

Yet, I've tried to do our part in the context of what we offer here at Tannin.

As you are now likely aware, we have gone to great efforts recently to educate our community about the origins of the botanical materials that we offer, and have even written detailed blogs on many of our botanicals, to give you as much detail possible on each one.

This gives you more information about our botanical materials, which can help you make more informed decisions about what to include in your aquariums- be they hardcore biotope, regional representational, "ecological", or whatever the hell you want to call them!

And I cannot stress it enough:

It's really important to enjoy aquariums the way YOU want to. That being said, however, I feel equally strong that it's important to learn about the biological interactions and functions of the habitats we attempt to replicate on some level in our aquariums. Understanding why the habitats that our fishes come from are the way they are- how they formed, etc., adds another, important level to understanding the fishes themselves.

And understanding the function of natural aquatic systems holds the key to understanding how to recreate, on many levels, the optimum aquarium habitats for our fishes, so that they may live healthy, normal lifespans, thrive, and maybe even reproduce under our care. You can call your tank a "biotope", "biotype", "theme"- whatever you want to...but every aquatic system is governed by the laws of Nature, and there is no real way around that. (even if you are of the opinion that "natural" processes don't occur in aquariums, lol)

You can't fight Nature.

I mean, you can try to defy her...For a while, at least. Mix incompatible species. "Force fit" wild fishes to adapt to your "tap water" conditions. Skip regular maintenance and husbandry routines. And then, just as sure as the water returns with the daily tide, She'll come back and spank you.

Yeah, it's foolish to do this.

Besides, why would you want to? I mean, part of the fun is seeing our fishes live in beautiful aquariums which represent the environments from which they come in the wild.

And guess what? You can call them whatever you want to. Just enjoy them. Learn from them. Share your knowledge and discoveries.

Stay resourceful. Stay bold. Stay excited. Stay engaged. Stay intrigued. Stay curious...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




September 18, 2019


Let them eat...botanicals!

Lately, we've been talking an awful lot about the environmental benefits of botanicals in our aquariums, and how they impart "functional aesthetics" to our systems. I think that's become not only more accepted in the hobby, it's backed up by a lot of scientific field studies. What is also studied by science, but a little more "esoteric" in the hobby (IMHO) is the use of botanicals as supplemental food for our fishes and shrimps. 

Now, it's known that most plant materials have nutritional value; or rather, they contain nutrients, vitamins, etc. which are known to be beneficial to aquatic organisms. Which ones are the best for use as "supplemental foods?"

Or, are they all pretty good? 


Well, here's the thing...

The thing that makes me curious is that most leaves and botanicals contain vitamins, amino acids, micronutrients, and other bioavailable compounds. The real question I have is exactly how "available" they are to our fishes and shrimp from a nutritional standpoint. And how "nutrient dense" these leaves and botanicals are? Do our fishes and shrimp easily assimilate all they need in every bite, or do they have to eat tons of the stuff to derive any of these benefits?

Big questions, right?

I mean, we as hobbyists sort of figure that if these things are present in the botanicals, then our animals get a dose of them in every bite, right? And, it begs the question: Are they really directly consuming stuff like Casuarina cones, or feeding on something else on their surfaces (more on this later)?

I think it's "yes" on both.

And the nutrition that they derive from consuming them?

Well, that's the part where I say, I don't know.

I mean, it seems to make a lot of sense to me...However, is there some definitive scientific information out there to prove this hypothesis?

A lot of the "botanicals for food thing" in the hobby (no, really- it's a "thing!") comes from the world of shrimp keepers. They've been touting this stuff in the hobby for a long time. A lot of it is based upon the presence of materials like leaves and such in the wild habitats where shrimp are found. I did some research online (that internet thing- I think it just might catch on...) and learned that in aquaculture of food shrimp, a tremendous variety of vegetables, fruits, etc. are utilized, and many offer good nutritional profiles for shrimp, in terms of protein, amino acids, etc.

They're all pretty good. Our friend Rachel O'Leary did a great job touching on the benefits of botanicals for shrimp in her video last Fall.

So, which one is the best? Is there one? Does it matter? In fact, other than sorting through mind-numbing numbers ( .08664, etc) on various amino acid concentrations in say, Mulberry leaves, versus say, Sugar Beets, or whatever, there are not huge differences making any one food superior to all others, at least from my very cursory, non-scientific hobby examination! 

Leaves like Guava, Mulberry, etc. ARE ravenously consumed by shrimp and some fishes. It's known by scientific analysis that they do contain compounds like Vitamins B1, B2, B6, and Vitamin C, as well as carbohydrates, fiber, amino acids, and elements such as Magnesium, Potassium, Zinc, Iron, and Calcium...all important for many organisms, including shrimp. Guava leaves are particularly good, according to some of the materials I read. Apparently, the bulk of the nutrients they contain are more "readily available" to animals than other leaves.

Well, that's pretty important, isn't it?

I think so!

Now, it may be coincidental that these much-loved (by the shrimp, anyways) leaves happen to have such a good amount of nutritional availability, but it certainly doesn't hurt, right?

Other leaves, such as Jackfruit, contain phytonutrients, such as lignans, isoflavones, and saponins that have health benefits that are wide ranging for humans. There is some conflicting data regarding Jackfruit's antifungal activity. However, the leaves are thought to exhibit a broad spectrum of antibacterial activity. In traditional medicine, these leaves are used to help heal wounds as well.

Do these properties transfer over to our fishes and shrimp?

We are not aware of any scientific studies that have been completed to correlate one way or another. That being said, they seem to flock to these leaves and graze on them and on the biofilms which accumulate on their surface tissues.

The "shrimp side" of the hobby reminds me in some ways of the coral part of the reef keeping hobby where I spent considerable time (both personally and professionally) working and interacting with the community. There are some incredibly talented shrimp people out there; many doing amazing work and sharing their expertise and experience with the hobby, to everyone's benefit!

Now, there are also a lot of people out there in that world -vendors, specifically- who make some (and this is just my opinion...), well - "stretches"- about products and such, and what they can do and why they are supposedly great for shrimp. I see a lot of this in the "food" sector of that hobby specialty, where manufacturers of various foods extoll the virtues of different products and natural materials because they have certain nutritional attributes, such as vitamins and amino acids and such, valuable to human nutrition, which are also known to be beneficial to shrimp in some manner. 

And that's fine, but where it gets a bit anecdotal, or - let's call it like I see it- "sketchy"- is when read the descriptions about stuff like leaves and such on vendors' websites which cater to these animals making very broad and expansive claims about their benefits, based simply on the fact that shrimp seem to eat them, and that they contain substances and compounds known to be beneficial from a "generic" nutritional standpoint- you know, like in humans.

All well-meaning, not intended to do harm to consumers...but perhaps occasionally, just a bit of a stretch.

I just wonder if we stretch and assert too much sometimes?

I'm not saying that it's "bad" to make inferences (we do it all the time with various topics- but we qualify them with stuff like,  "it could be possible that.." or "I wonder if..."), but I can't stand when absolute assertions are made without any qualification that, just because this leaf has some compound which is part of a family of compounds that are thought to be useful to shrimp, or that shrimp devour them...that it's a "perfect" food for them. 

It's just a food- one of many possibilities out there.

Of course, I hope I'm not out there adding to the confusion! We try to hold ourselves to higher standards on this topic; yet, like so many things we talk about in the world of botanicals, there are no absolutes here.

What is fact is that some botanical/plant-derived materials, such as various seeds, root vegetables, etc., do have different levels of elements such as calcium and phosphorous, and widely varying crude protein. Stuff that's known to be beneficial to shrimp, of course. These things are known by science. Yet, I have no idea what some of the seed pods we offer as botanicals contain in terms of proteins or amino acids, and make no assertions about this aspect of them, above and beyond what I can find in scientific literature.

However, I suppose that one can make some huge over-generalizations that one seedpod/fruit capsule is somewhat similar to others, in terms of their "profile" of basic amino acids, vitamins, trace elements, etc. (gulp). We can certainly assume that some of this stuff, known to have nutritional value, can make these materials potentially useful as a supplemental food source for fishes and shrimps.

Yet, IMHO that's really the best that we can do until more specific, scientifically rigid studies are conducted.

Now, we may not know which seed pods and such in and of themselves are more nutritious to fishes and shrimp than others, but we DO know from simple observation that some are better at "recruiting" materials on their surfaces which serve as food sources for aquatic organisms!

Yeah, I'm talking about the biofilms and fungal growth, which make their appearance on our botanicals, leaves, and wood after a few weeks of submersion...

As we've talked about repeatedly, biofilms are not only typically harmless in aquariums, they are utilized as a supplemental food source by a huge variety of fishes and shrimps in both Nature and the aquarium. They are a rich source of sugars and other nutrients, and could prove to be an interesting addition to a "nursery tank" for raising fry if kept in control. Like, add a bunch of leaves and botanicals, let them do their thing, and allow your fry to graze on them!

Don't believe me?

Ask almost any shrimp keeper-they'll "sing the praises" of biofilm for the "grazing" aspect!

And of course, it's long been known from field studies that as leaves and other plant materials break down, they serve as "fuel" for the growth of biofilm, fungi and microorganisms...which, in turn, provide supplemental food for our fishes. I've seen a bunch of videos of shrimps and fishes in the wild "grazing" over fields of decomposing leaves and the biofilms they foster.

Ahh, biofilms again.


Biofilms form when bacteria adhere to surfaces in some form of watery environment and begin to excrete a slimy, gluelike substance, consisting of sugars and other substances, that can stick to all kinds of materials, such as- well- in our case, botanicals.

Biofilms on decomposing leaves are pretty much the foundation for the food webs in rivers and streams throughout the world. They are of fundamental importance to aquatic life.

It starts with a few bacteria, taking advantage of the abundant and comfy surface area that leaves, seed pods, and even driftwood offer. The "early adapters" put out the "welcome mat" for other bacteria by providing more diverse adhesion sites, such as a matrix of sugars that holds the biofilm together. Since some bacteria species are incapable of attaching to a surface on their own, they often anchor themselves to the matrix or directly to their friends who arrived at the party first.

Sorta sounds like Facebook, huh?

(The above graphic from a scholarly article illustrates just how these guys roll.)

And we know from years of personal experience and observation in the aquarium that fishes and shrimp will consume them directly, removing them from virtually any surface they form on.

And some materials are likely better than others at recruiting and accumulating biofilm growth. The "biofilm-friendly" botanical items seem to fall into several distinct categories: Botanicals with hard, relatively impermeable surfaces,  softer, more ephemeral botanical materials which break down easily, and hard-skinned botanicals with soft interiors, and...

Okay, wait- that kind of covers like, everything, lol.


What that tells ME, the over-caffeinated, perhaps somewhat under-educated armchair "scientist"-wannabe, is that most of the botanicals we offer here at Tannin- in addition to being potentially consumed directly by aquatic organisms- likely also have some capability of recruiting biofilms.

And the idea of biofilms and such being an excellent supplemental food source for shrimp-and fishes- is not's just something that we're finally getting around to agreeing about with our little friends! (And with the shrimp people, too)

Nothing is wasted in Nature, right?

To you, my fishy friends, I say, "Let them eat botanicals!" (well, at least as part of their diet, anyways!)- and the materials which accumulate on their surfaces, too!

Let's try not to make too many assumptions, or buy too heavily into vendors' marketing hyperbole- at least, not without doing some of our own research and "field work."

As hobbyists, let's continue to experiment, observe, learn from, and share our experiences and observations with others. 

We all win from that.

In fact, that's likely the one absolute assertion I will make!

Stay curious. Stay disciplined. Stay objective. Stay experimental...

And Stay Wet.


Scott Fellman

Tannin Aquatics 





September 17, 2019


Bottom-up evolution...

Don't you just love the idea of "tweaking" your aquariums from time to time? You know, working with new ideas that might create some different outcomes in existing tanks...or even just starting new tanks with completely different ideas and running with them.

I guess it's sort of my "process", right?

Like many of you, I'm constantly "iterating", or in our language, "evolving" my aquariums to embrace new ideas, concepts, or aesthetics which I think would push the "state of the art" of blackwater/botanical-style aquariums down the road a bit.

Lately, I've been thinking about an even more realistic-looking-and functioning- "flooded forest" themed aquarium, something we're seeing more and more of our community playing with. And, part of my experimentation has been playing with different substrate compositions, depths, and particle sizes.

And, while playing with those ideas, I've been thinking through further refinements of the "deep botanical bed"/sand substrate relationship. I've been spending a lot of time researching the natural systems and contemplating how we can translate some of this stuff into our closed system aquaria.

Now, I realize, when contemplating really deep aggregations of substrate materials in the aquarium, that we're dealing with closed systems, and the dynamics which affect them are way different than those in Nature, for the most part.

And I realize that experimenting with these unusual substrates requires not only a sense of adventure, a direction, and some discipline- but a willingness to accept and deal with an entirely different aesthetic than what we know and love. And this also includes pushing into areas and ideas which might make us uncomfortable, not just for the way they look, but for what we are told might be possible risks.

One of the things that many hobbyists ponder when we contemplate creating deep, botanical-heavy substrates, consisting of leaves, sand, and other botanical materials is the buildup of hydrogen sulfide, CO2, and other undesirable compounds within the substrate.

Well, it does make sense that if you have a large amount of decomposing material in an aquarium, that some of these compounds are going to accumulate in heavily-"active" substrates. Now, the big "bogeyman" that we all seem to zero in on in our "sum of all fears" scenarios is hydrogen sulfide, which results from bacterial breakdown of organic matter in the total absence of oxygen.

Let's think about this for just a second.

In a botanical bed with materials placed on the substrate, or loosely mixed into the top layers, will it all "pack down" enough to the point where there is a complete lack of oxygen and we develop a significant amount of this reviled compound in our tanks? I think that we're more likely to see some oxygen in this layer of materials, and I can't help but speculate- and it IS just speculation- that actual de-nitirifcation (nitrate reduction), which lowers nitrates while producing free nitrogen, might actually be able to occur in a "deep botanical" bed.

And it's certainly possible to have denitrification without dangerous hydrogen sulfide levels. As long as even very small amounts of oxygen and nitrates can penetrate into the substrate this will not become an issue for most systems. I have yet to see a botanical-style aquarium where the material has become so "compacted" as to appear to have no circulation whatsoever within the botanical layer.

Now, sure, I'm not a scientist, and I base this on close visual inspection of numerous aquariums, and the basic chemical tests I've run on my systems under a variety of circumstances. As one who has made it a point to keep my botanical-style aquariums in operations for very extended time frames, I think this is significant. The "bad" side effects we're talking about should manifest over these longer time frames...and they just haven't.

And then there's the question of nitrate. Although not the terror that ammonia and nitrite are known to be, nitrate is much less so. However, as nitrate accumulates, fish will eventually suffer some health issues. Ideally, we strive to keep our nitrate levels no higher than 5-10ppm in our aquariums.  As a reef aquarist, I've always been of the "...keep it as close to zero as possible." mindset, but that is not always the most realistic or achievable target in a heavily-botanical-laden aquarium. You have a bit more "wiggle room", IMHO. Now, when you start creeping towards 50ppm, you're getting closer towards a number that should alert you. It's not a big "stretch" from 50ppm to 75ppm and higher...

And then you get towards the range where health issues could manifest themselves in your fishes. Now, many fishes will not show any symptoms of nitrate poisoning until the nitrate level reaches 100 ppm or more. However,  studies have shown that long-term exposure to concentrations of nitrate stresses fishes, making them more susceptible to disease, affecting their growth rates, and inhibiting spawning in many species. 

At those really high nitrate levels, fishes will become noticeably lethargic, and may have other health issues that are obvious upon visual inspection, such as open sores or reddish patches on their skin. And then, you'd have those "mysterious deaths" and the sudden death (essentially from shock) of newly-added fishes to the aquarium, because they're not acclimated to the higher nitrate concentrations.

Okay, that's scary stuff. However, high nitrate concentrations are not only manageable- they're something that's completely avoidable in our aquairums.

Quite honestly, even in the most heavily-botanical-laden systems I've played with, I have personally never seen a higher nitrate reading than around 5ppm. I attribute this to  common sense stuff: Good quality source water (RO/DI), careful stocking, feeding, good circulation, and consistent basic aquarium husbandry practices (water changes, filter maintenance, etc.).

Now, that's just me. I'm no scientist, certainly not a chemist, but I have a basic understanding of maintaining a healthy nitrogen cycle in the aquarium. And I am habitual-perhaps even obsessive- about consistent maintenance. Water exchanges are not a "when I get around to it" thing in my aquarium management "playbook"- they're "baked in" to my practice.

So yeah, although nitrate is a concern in botanical-style aquariums, it need not be an ominous cloud hanging over our success. In my opinion, the far more problematic issues with botanicals and water quality are related to lapses in our own good judgment and to misguided practices. Experience with our customer base tends to confirm this, too.

The very few issues that we've seen with people "pushing it too far" in terms of botanical applications, were caused by rapid influxes of large quantities of botanical materials to existing, stable aquariums, which, I believe, overwhelmed the resident bacterial population and might have resulted in rapid oxygen depletion and a corresponding increase in CO2. The result was fishes hanging at the surface in an attempt to get oxygen. The good news was that almost every situation like this I heard of was remedied in a relatively short period of time by adding additional aeration into the tank, a series of water exchanges, and/or removing some of the materials.

Generally, loss of life was minimal (that's an awful term, though) or nonexistent as a result of these measures. Regardless, it's really important to be careful. Fish can die if we push it too hard.  It's not just "Boil, dump...Instant Amazon..."  Measured implementation and experimentation is required when using botanicals. We're often adding biological materials to established aquariums, which might not be able to handle large, fast influxes.

There's obviously some "upper limit" of how much botanical material we can add to a given established  system in a brief period of time, and it's especially more profound in newly-established aquariums with "immature" nutrient export mechanisms in place.

Typically, most botanical-"powered" systems run trouble free, especially when you understand what's going on, know what to expect (yeah, decomposing leaves, biofilms, etc.), and have mechanisms in place to accommodate them.

Now, this is not to say that you can't have some disasters if you "go too hard" or "too fast" with lots of botanicals in a closed system. It just makes sense, right? You're adding material which will decompose in the water, and if adequate nutrient export systems are not in place to deal with it, you could have some problems. This isn't some new revelation; it's something we've been talking about here for a long time.

And it's common sense- "Aquarium-Keeping 101", really. However, it's important to bring up the potential "dark sides" of botanical-style aquariums now and again, as more and more hobbyists start experimenting with this stuff.

What kinds of things can we do to prevent problems like this?

Well, for one thing, we can add botanical materials gradually, at a slow, steady pace. This will give our bacteria population a chance to catch up with the influx of materials being added. Also, it will slow down the pace of any pH fluctuations (assuming we are utilizing stuff that can lower the pH in our tanks) so that the fishes can adjust to them.

It's common sense "best practice" for us.

Another thing would be to employ good circulation within your system, which not only results in greater oxygenation and "mixing" of water "strata" - it physically suspends fine particulates in your system as well, making it easier for mechanical filtration to remove (of course, that assumes you don't like the look of "stuff" in the water, as some of us do!).

So, back to the substrate again...

Relatively shallow sand beds seem to be optimal for denitrification, and many of us employ them for the aesthetics as well. Light "vacuuming" of the top layers to remove any potential "dead spots" is always a good practice, IMHO. Any debris stirred up can easily be removed mechanically by filtration, as mentioned above. Of course, you don't have to go crazy siphoning the hell out of your sand every week, essentially decimating populations of beneficial microscopic infauna -or interfering with their function- in the process.

Now, I think one of the most "liberating" things we've seen in the blackwater, botanical-style aquarium niche is our practice of utilizing the substrate itself to become a feature aesthetic point in our aquariums, as well as a functional mechanism for the inhabitants.


In other words, in a strictly aesthetic sense, the bottom itself becomes a big part of the aesthetic focus of the aquarium, with the botanicals placed upon the substrate- or, in some cases, becoming the substrate! These materials form an attractive, texturally varied "micro-scape" of their own, creating color, interest, and functions that we are just starting to appreciate. In fact, I dare say that one of the next "frontiers" in our niche would be an aquarium which is just substrate materials, without any "vertical relief" provide by wood or rocks.

I've executed a few aquariums based on this idea (specifically, with leaves), and I've been extremely happy with their long-term performance! Oh, and they kind of looked cool, too...

Nature provides no shortage of habitats with unusual substrate composition for inspiration. If we look at them in context of the surrounding terrestrial ecosystem, there are a lot of possible "functional takeaways" that we as hobbyists can apply to our aquarium work.

And the interesting thing about these features, from an aesthetic standpoint, is that they create an incredibly alluring look with a minimum of "design" required on the hobbyists part. Remember, you can to put together a substrate with a perfect aesthetic mix of colors and textures, but that's about it.

We have to "cede" some of the "work" to nature at that point!

Once your substrate is in place, Nature takes over and the materials develop that lovely "patina" of biofilms and microbial growth, and start breaking down. Some may be moved about by the grazing activities of resident fishes, or otherwise slowly redistributed around the aquarium.

A literal "active substrate", indeed! Yet, something that is fascinating and beautiful for those who give the idea a shot!

This is a big aesthetic shift in the hobby, but it goes well beyond that.

I mean, sure, we've done hardscapes before, with wood and stones dominating the 'scape.  Aesthetics are great. They create alluring aquariums. However, our tanks have placed far more emphasis on the "functional" aspects of the botanical materials we use. The aesthetics just sort of go with the territory. 

Ahh, the "function" part of the equation...

Much like in the wild aquatic habitats of the world, the materials that we place on the bottom of the aquarium will become an active, integral part of the ecosystem. From a "functional" standpoint, substrates comprised of various grades of sands, muds, and silts, supplemented with a variety of botanical materials, form a sort of "in-tank refugium", which allows small aquatic crustaceans, fungi, and other microorganisms to multiply and provide supplemental food for the aquarium, as we've touched on before.

Just like in Nature.

They've become not only physical places for fishes to hide and forage among- they've become an integral part of the entire closed aquarium ecosystem itself, helping influence water parameters, foster growth of nutrient-processing fungi and microorganisms, and just maybe- some form of nutrient export/denitrification (although that last part is still a bit speculative).

It's certainly no stretch to call our use of botanicals as a form of "active substrate", much like the use of clays, mineral additives, soils, etc. in planted aquariums. Although our emphasis is on creating specific water conditions, fostering the growth of microorganisms and fungi, as well as creating unique aesthetics, versus the "more traditional" substrate materials fostering conditions specifically for plant growth.

Of course, there is nothing saying that you can't incorporate the best of both worlds, to create aquariums which offer our fishes AND our plants optimum environmental conditions in which to grow and multiply.

And, as we play more with botanicals, we're finding out more unique ways to work with interesting materials to create substrate-centric systems that check all the boxes: Functionality. Interest. Aesthetics. Stability.

We've just scratched the surface about the "functional aesthetics" created by botanicals in the aquarium, and the potential for additional biological support/filtration (and potentially even denitrification), and it's a big, BIG topic, with lots more to be explored, discovered and deployed in our aquariums!

Flirting with a "substrate-centric" tank is one of those tantalizing, at first seemingly awkward, yet ultimately transformational little projects we can play with. 

And then there is the use of aquatic plants; something that we are seeing more and more of in botanical-oriented systems. In fact, it's becoming a real "standard" in our world- as it should be- as it realistically represents many of the wild habitats from which our fishes hail.

In terms of impact on the substrate, it's a known fact that plants remove ammonia directly, and typically will prevent the anaerobic conditions that promote production of hydrogen sulfide within the substrate itself. So there are many benefits to including them in our botanical-style blackwater aquariums!

 In summary, the simple practice of adding "botanical stuff" into our aquariums is not some "high concept thing." However, the impacts on the water chemistry and overall aquatic environment- not to mention, on our fishes- are profound, fascinating, and real!

Being careful and taking the time to clean, prepare, and add botanicals to your aquarium in a measured manner always yields a better outcome. Going slowly also gives you the opportunity to address any issues that you might have before they become critical, especially when you're experimenting with some of these ideas.

It just makes sense to be patient. The rewards are so great.

We as an enthusiastic and engaged global community have slowly and carefully taken the concept of a blackwater, botanical-style aquarium out of the realm of "carnival side show" into an evolving, legitimate practice to achieve significant results with our treasured fishes. We continuously see reports of dramatic fish health improvements, spawnings of delicate species, seen wonderful, realistic representations of nature, even experienced an occasional tragedy or two on very rare occasions...and realized from each- that we learn.

And we recognize that we are all part of a greater whole, and that the work that we're doing will benefit the generations of aquarists who will follow us, and apply what we're learning in ways that we probably haven't even contemplated yet. Thinking about things like botanical-infused substrates are just one way to push the state of the art along.

Yeah, it's a hobby evolution...from the bottom up.

Glad to have you in the mix!

Stay creative. Stay enthusiastic. Stay bold. Stay curious. Stay engaged...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



September 16, 2019


The dynamics of the botanical-style aquarium...

The most interesting thing about botanical-style aquariums, particularly from the perspective of an aquascaper, is that they are not "static" systems. In other words, almost from the minute you set them up, they begin changing..."evolving", as our community likes to say. Not unlike planted aquariums in some respects, purely botanical-style systems are highly dynamic, and look slightly different each and every day.

Oh sure, the "permanent" hardscape- the wood, the rocks (if you use them) are not going anywhere; typically, not changing much, with the exception of "recruiting" biofilms and perhaps a "patina" of algae over time. However, by-and-large, the rest of the 'scape- leaves, seed pods, twigs, etc., starts to soften, break down, recruit biofilms, and are moved about by current and the activities of resident fishes.

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 not have: The "topping off" of botanicals as they break down.

It's a regular thing; almost a revered, ritualistic sort of thing among us hardcore botanical-style aquarium freaks.

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.

Nature does it's own version of this "topping-off" process, too, of course!

Many bodies of water which meander through jungles and rain forests are constantly being "restocked" with leaves, seed pods, branches, and other botanical materials from the surrounding vegetation- some of which are knocked into the water by weather, wind, animal activity, etc. Depending upon the velocity of the water, its depth, etc., they may aggregate right where they fall, or be gradually re-distributed downstream by the current.

Interestingly, in places like the rain forest streams of Amazonia, biologists have observed floating leaf litter beds which hold together for quite a long time- almost becoming known "features" in the aquatic "topography" of the igarapes and streams of the region!

So imagine, if you will, a "classic" submerged leaf litter bed in Amazonia, composed of a variety of leaves, branches, twigs, seed pods, and other botanical materials...Yet, floating on the water surface; extending as much as a few feet under the water! What you get is a fairly deep layer of plant materials colonized by fishes and other creatures, which forage on the macro invertebrate life found in these complex assemblages.

Biologists call this an "ephemeral" habitat, as it is transitory or temporary as it slowly breaks apart-despite the fact that it might be years before this occurs.

Okay, so it slowly breaks apart over months and months.

And often, these floating or partially submerged leaf litter banks either accumulate among the branches of overhanging vegetation during the high-water season, gradually floating downstream, or they stay anchored in place by fallen tree trunks and other large materials, ultimately forming a more "traditional" submerged leaf litter bed as they sink.

Think about the possibilities to replicate them in aquariums!

I found this to be an amazingly interesting niche! Reminds me of the Sargassum "forests" of the Caribbean and Tropical West Atlantic! Literal "floating feasts" for the animals which reside there! This is another potentially irresistible ecological niche for us to play with, right?

Oh- and many fish species associate with these floating litter banks for the entire wet season! 

And one of the reasons they stay put is because their food sources are there, too! In fact, a species of "water bug", Weberiella rhomboides, is found almost exclusively in these floating banks, attracting large numbers of insectivorous fishes, like characins, catfishes, knife fishes, and others. 

Yeah, it's a virtual "who's who" of blackwater, leaf-litter-zone dwellers, some of which are very familiar to us as hobbyists- for example, characins like Hemmigramusspecies, Moenkhausia species, the killifish Rivulus ornatus, and of course, cichlids, including a number of ApistogrammaCrenicichla, Hypselecara, and the much-loved Mesonauta festivus, to name a few. Can you imagine how this could make a very interesting theme for an aquarium?

Yeah, I you'd imagine!

You'd want a fairly shallow, wide aquarium, and probably would filter it with an outside power filter or canister filter with the return positioned in such a way as to minimally disturb the surface. With minimal preparation (ie; cleaning them with a light boil, but not trying to saturate them to the point of the materials sinking right to the bottom), a lot of this stuff would sort of float for a while before sinking to the bottom.

You'd essentially be creating a diverse assemblage of botanicals, just like you would if you were doing a "conventional" leaf-litter display (I love that- I just called this stuff a "conventional leaf litter display"- look how far we've come..WTF.). And of course, Nature offers no shortage of inspiring leaf-litter habitats to examine!

Now, eventually, some of this stuff would sink, or be trapped below the floating "matrix", and you'd end up with materials on the!  It would transition naturally to a more "conventional" botanicals-on-the-bottom display. So this is essentially an "ephemeral display"- transitioning from a "floating leaf litter bed" to a submerged leaf-litter aquarium!

How freakin' cool is that? Of course, you could probably keep it going by replacing the leaves and such as you would anyways, right? And as the wood becomes submerged, you'd "let it do it's thing", and/or replace/add new pieces.

Sure, I digressed a bit...What else is new?

The point is, the wild habitats 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 the phenomenon is not limited to Amazonainan forests, of course. We see the same thing occurring in "mangals"- habitats in which mangroves dominate.

Falling leaves and botanical materials, accumulating, decomposing, and being re-distributed by natural forces is a constant process, helping to enrich the overall habitat for a myriad of organisms. The eco diversity and productivity of mangrove habitats- like many habitats in which leaves and botanical materials accumulate underwater- is remarkable.

I've  seen this phenomenon of leaves dropping naturally (and supplemented by me as well) in my mangrove inspired brackish-water aquarium. In the year or so of operation, I'd see a lot of this type of "evolution" occurring daily. 

Truly a dynamic habitat for fishes. 

Perhaps one of the more completely "functionally aesthetic" aquariums I've built in many years, the brackish tank has really put this function/process "front and center", giving me a "ringside seat" of an evolving brackish microcosm!

Leaves fall, break down, and become a food resource and physical shelter for the fishes and animals which reside in the aquaria, just like in Nature.

And of course, the idea of botanicals accumulating in our aquariums, impacting both the biological diversity and function of them, is a big part about what the excitement of the botanical-style aquarium is all about!

It's not just the unique aesthetics...It's the function that they bring- and the possibilities that accompany them!

We're now at a phase where enough people have gotten through the "Will this kill my fish?" part of the equation, and we've moved on to "How can I facilitate maximum benefits to my fishes with a blackwater, botanical-style aquarium?"

The point of all of this stuff is that the botanical-style aquariums we love so much are truly dynamic habitats, constantly changing and evolving- much like they do in Nature! The ability to replicate the look, the characteristics, and the function of Nature in our aquariums is an amazing process that will benefit the larger aquarium hobby in ways not even fully realized at this time.


It's a time for more great experimentation. More discovery. And further exploration of the potential of providing our fishes with what might be the most natural simulation of Nature possible.

It's truly an exciting time to be in the hobby- especially in our "sector!"

And, yeah- YOU are right in the thick of it! 

Stay inspired. Stay involved. Stay excited. Stay creative. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics