As the seasons pass...


Every Corydoras breeder knows something that we all should know:

Environmental manipulations create unique opportunities to facilitate behavioral changes in our fishes.

It's hardly an earth-shattering idea in the aquarium hobby, but I think that the concept of "seasonal" environmental manipulation deserves some additional consideration.

It's been known for decades that environmental changes to the aquatic environment caused by weather (particularly "wet" or "dry" seasons/events) can stimulate fishes into spawning. 

As a fish geek keen on not only replicating the look of our fishes' wild habitats, but as much of the "function" as possible, I can't help myself but to ponder the possibilities for greater success by manipulating the aquarium environment to simulate what happens in the wild.

Probably the group of aquarists who has had the most experience and success at incorporating such environmental manipulations into their breeding procedures is Corydoras catfish enthusiasts! 

Many hobbyists who have bred Corydoras utilize the old trick of a 20%-30% water exchange with water that is up to 10° F cooler (6.5° C) than the aquarium water is normally maintained at. It seems almost like one of those, "Are you &^%$#@ crazy- a sudden lowering of temperature?"

However, it works, and you almost never hear of any fishes being lost as a result of such manipulations.

I often wondered what the rationale behind such a change was. My understanding is that it essentially is meant to mimic a rainstorm, in which an influx of cooler water is a feature. Makes sense. Weather conditions are such an important part of the life cycle of our fishes.

Still others attempt to simulate a "dry spell" by allowing the water quality to "degrade" somewhat (what exactly that means isoprene to interpretation!), while simultaneously increasing the aquarium temperature a degree or two. This is followed by a water exchange with softer water (ie; pure RO/DI), and resetting the tank temp to the tank's normal range of parameters.

The "variation" I have heard is to do the above procedure, accompanied by an increase in current via a filter return or powerhead, which simulates the increased water volume/flow brought on by the influx of "rain."


Many breeders will fast their fishes a few days, followed by a big binge of food after the temperature drop, apparently simulating the increased amount of food in the native waters when rains come.

Still other hobbyists will reduce the pH of their aquarium water to stimulate breeding. And I suppose the rationale behind this is once again to simulate an influx of water from rain or other external sources...

Weather, once again.

And another trick I hear from my Cory breeder friends from time to time is the idea of tossing in a few alder cones into the tank/vessel where their breeders' eggs are incubating.

This decades-old practice is justified by the assertion that the alder cones possess some type of anti-fungal properties...not entirely off base with some of the scientific research we've found about the allegedly anti-microbial/antifungal properties of catappa leaves and such...

And of course, I hear/read of recommendations to use the aforementioned catappa leaves, oak leaves, and Magnolia leaves for just this purpose...


Okay, cool.

Not really earth-shattering; however, it got me thinking about the whole idea of environmental manipulations as part of the routine "operation" of our botanical-mehtod aquariums.....Should we create true seasonal variations for our aquariums as part of our regular practice- not just when trying to spawn fishes? I mean, changing up lighting duration, intensity, angles, colors, increasing/decreasing water levels or flow?

With all of the high tech LED lighting systems, electronically controlled pumps; even advanced heaters- we can vary environmental conditions to mimic what occurs in our fishes' natural habitats during seasonal changes as never before. I think it would be very interesting to see what kinds of results we could get with our fishes if we went further into seasonal environmental manipulations than we have been able to before.

And of course, if we look at the natural habitats where many of our fishes originate, we see these seasonal changes having huge impact on the aquatic ecosystems. In The Amazon, for example, the high water season runs December through April.

And during the flooding season, the average temperature is 86 degrees F, around 12 degrees cooler than the dry season. And during the wet season, the streams and rivers can be between 6-7 meters higher on the average than they are during the dry season! 

And of course, there are more fruits, flowers, and insects during this time of year- important food items for many species of fishes.

And the dry season? Well, that obviously means lower water levels, higher temperatures, and abundance of fishes, most engaging in spawning activity. 

Mud and algal growth on plants, rocks, submerged trees, etc. is quite abundant in these waters at various times of the year. Mud and detritus are transported via the overflowing rivers into flooded areas, and contribute to the forest leaf litter and other botanical materials, coming nutrient sources which contribute to the growth of this epiphytic algae. 

During the lower water periods, this "organic layer" helps compensate for the shortage of other food sources. When the water is at a high period and the forests are inundated, many terrestrial insects fall into the water and are consumed by fishes. In general, insects- both terrestrial and aquatic, support a large community of fishes.

So, it goes without saying that the importance of insects and fruits- which are essentially derived from the flooded forests, are reduced during the dry season when fishes are confined to open water and feed on different materials. 

So I part of the key to successfully conditioning and breeding some of the fishes found in these habitats altering their diets to mimic the seasonal importance/scarcity of various food items? In other words, feeding more insects at one time of the year, and perhaps allowing fishes to graze on detritus and biocover at other times?

And then, there are those fishes whose life cycle is intimately tied into the seasonal changes.

The killifishes.

Any annual or semi-annual killifish species enthusiast will tell you a dozen ways to dry-incubate eggs; again, a beautiful simulation of what happens in Nature...So much of the idea can be applicable to other areas of aquarium practice, right? 

Yeah... I think so.

It's pretty clear that factors such as the air, water and even soil temperatures, atmospheric humidity, the water level, the local winds as well as climatic variables have profound influence on the life cycle and reproductive behavior on the fishes that reside in these dynamic tropical environments! 

In my "Urban Igapo" experiments, we get to see a little microcosm of this whole seasonal process and the influences of "weather."

And of course, all of this ties into the intimate relationship between land and water, doesn't it?

There's been a fair amount of research and speculation by both scientists and hobbyists about the processes which occur when terrestrial materials like leaves and botanical items enter aquatic environments, and most of it is based upon field observations.

As hobbyists, we have a unique opportunity to observe firsthand the impact and affects of this material in our own aquariums! I love this aspect of our "practice", as it creates really interesting possibilities to embrace and create more naturally-functioning systems, while possibly even "validating" the field work done by scientists!

And of course, there are a lot of interesting bits of information that we can interpret from Nature when planning, creating, and operating our aquariums.

It goes without saying that there are implications for both the biology and chemistry of the aquatic habitats when leaves and other botanical materials enter them. Many of these are things that we as hobbyists observe every day in our aquariums!


A lab study I came upon found out that, when leaves are saturated in water, biofilm is at it's peak when other nutrients (i.e.; nitrate, phosphate, etc.) tested at their lowest limits. This is interesting to me, because it seems that, in our botanical method aquariums, biofilms tend to occur early on, when one would assume that these compounds are at their highest concentrations, right? And biofilms are essentially the byproduct of bacterial colonization, meaning that there must be a lot of "food" for the bacteria at some point if there is a lot of biofilm, right?

More questions...

Does this imply that the biofilms arrive on the scene and peak out really quickly; an indication that there is actually less nutrient in the water? Is the nutrient bound up in the biofilms? And when our fishes and other animals consume them, does this provide a significant source of sustenance for them?


Oh, and here is another interesting observation:

When leaves fall into streams, field studies have shown that their nitrogen content typically will increase. Why is this important? Scientists see this as evidence of microbial colonization, which is correlated by a measured increase in oxygen consumption. This is interesting to me, because the rare "disasters" that we see in our tanks (when we do see them, of course, which fortunately isn't very often at all)- are usually caused by the hobbyist adding a really large quantity of leaves at once, resulting in the fishes gasping at the surface- a sign of...oxygen depletion?

Makes sense, right? 

These are interesting clues about the process of decomposition of leaves when they enter into our aquatic ecosystems. They have implications for our use of botanicals and the way we manage our aquariums. I think that the simple fact that pH and oxygen tend to go down quickly when leaves are  initially submerged in pure water during lab tests gives us an idea as to what to expect.

A lot of the initial environmental changes will happen rather rapidly, and then stabilize over time. Which of course, leads me to conclude that the development of sufficient populations of organisms to process the incoming botanical load is a critical part of the establishment of our botanical-method aquariums.

Fungal populations are as important in the process of breaking down leaves and botanical materials in water as are higher organisms, like insects and crustaceans, which function as "shredders." The “shredders” – the animals which feed upon the materials that fall into the streams, process this stuff into what scientists call “fine particulate organic matter.”

And that's where fungi and other microorganisms  make use of the leaves and materials, processing them into fine sediments. Allochthonous material can also include dissolved organic matter (DOM) carried into streams and re-distributed by water movement.

And the process happens surprisingly quickly.

In studies carried out in tropical  rainforests in Venezuela, decomposition rates were really fast, with 50% of leaf mass lost in less than 10 days! Interesting, but is it tremendously surprising to us as botanical-style aquarium enthusiasts? I mean, we see leaves begin to soften and break down in a matter of a couple of weeks- with complete breakdown happening typically in a month or so for many leaves.

And biofilms, fungi, and algae are still found in our aquariums in significant quantities throughout the process.

So, what's this all mean? What are the implications for aquariums? 

I think it means that we need to continue to foster the biological diversity of animals in our aquariums- embracing life at all levels- from bacteria to fungi to crustaceans to worms, and ultimately, our fishes...All forming the basis of a closed ecosystem, and perhaps a "food web" of sorts for our little aquatic microcosms. It's a very interesting  concept- a fascinating field for research for aquarists, and we all have the opportunity to participate in this on a most intimate level by simply observing what's happening in our aquariums every day!

We've talked about this very topic many times right here over the years, haven't we? I can't let it go.

Bioversity is interesting enough, but when you factor in seasonal changes and cycles, it becomes an almost "foundational" component for a new way of running our botanical-style aquariums.

Consider this:

The wet season in The Amazon runs from November to June. And it rains almost every day.

And what's really interesting is that the surrounding Amazon rain forest is estimated by some scientists to create as much as 50% of its own precipitation! It does this via the humidity present in the forest itself, from the water vapor present on plant leaves- which contributes to the formation of rain clouds.

Yeah, trees in the Amazon release enough moisture through photosynthesis to create low-level clouds and literally generate rain, according to a recent study published in the Proceedings of the National Academy of Sciences (U.S.)!

That's crazy.

But it makes a lot of sense, right?

Okay, that's a cool "cocktail party sound bite" and all, but what happens to the (aquatic) environment in which our fishes live in when it rains?

Well, for one thing, rain performs the dual function of diluting organics, while transporting more nutrient and materials across the ecosystem. What happens in many of the regions of Amazonia - and likewise, in many tropical locales worldwide-is the evolution of some of our most compelling environmental niches...

We've literally scratched the surface, and the opportunity to apply what we know about the climates and seasonal changes which occur where our fishes originate, and to incorporate, on a broader scale, the practices which our Corydoras-enthusiast friends employ on all sorts of fishes!

So much to learn, experiment with, and execute on.

Stay fascinated. Stay intrigued. Stay observant. Stay creative. Stay astute...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




noun- The establishment or starting point of an institution or activity.


We've had a lot of requests lately to discuss how we start up our botanical method aquariums. Now sure, we've covered this topic before over the years; yet, as our practices have evolved, so has our understanding about why we do things the way that we do- and why it works.

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

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

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

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

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

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

I mean, sure, you want to rinse sand as clean as possible. You want make sure that you have a piece of wood that's been soaked for a while, and..

Wait, DO you?

I mean, sure, if you don't rinse your sand carefully, you'll get some cloudy water for argument there.

And if you don't clean your driftwood carefully, you're liable to have some soil or other "dirt" get into your system, and more tannins being released, which leads to...well, what does it lead to?

I mean, an aquarium is not a "sterile" habitat. Let's not fool ourselves.

The natural aquatic habits which we attempt to emulate, although comprised of many millions of times the volumes of water volume and throughput that we have in our tanks- are typically not "pristine"- right? I mean, soils from the surrounding terrestrial environment carry with them decomposing matter, leaves, etc, all of which impact the chemistry, oxygen-carrying capacity, biological activity, and of course, the visual appearance of the water.

And that's kind of what our whole botanical-method aquarium adventure is all about- utilizing the "imperfect" nature of the materials at our disposal, and fostering and appreciating the natural interactions between the terrestrial and aquatic realms which occur.

Of course, much like Nature, our botanical-method aquariums make use of the "ingredients" found in the abundant materials which comprise the environment. And the "infusion" of these materials into the water, and the resulting biological processes which occur, are what literally make our tanks come alive.

And yeah, it all starts with the nitrogen cycle...

We can embrace the mindset that every leaf, every piece of wood, every bit of substrate in our aquariums is actually a sort of "catalyst" for sparking biodiversity, function, and yes- a new view of aesthetics in our aquariums.

I'm not saying that we should NOT rinse sand, or soak wood before adding it to our tanks. What I AM suggesting is that we don't "lose our shit" if our water gets a little bit turbid or there is a bit of botanical detritus accumulating on the substrate. And guess what? We don't have to start a tank with brand new, right-from-the-bag substrate.

Of course not.

We can utilize some old substrate from another tank (we have done this as a hobby for decades for the purpose of "jump starting" bacterial growth) which also has the side benefit of providing a different aesthetic as well!

And, you can/should take it further: Use that slightly algal-covered piece of driftwood or rock in our brand new tank...This gives a more "broken-in look", and helps foster a habitat more favorable to the growth of the microorganisms, fungi, and other creatures which comprise an important part of our closed aquarium ecosystems.

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

It's perfectly okay for your tank to look a bit "worn" right from the start. Functional aesthetics once again! the look results from the function.

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

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

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

I am operating on the assumption (gulp) that most of us have a  basic understanding of the nitrogen cycle and how it impacts our aquariums. However, maybe we don’t all have that understanding. My ramblings have been labeled as “moronic” by at least one “critic” before, however, so it’s no biggie for me as said “moron” to give a very over-simplified review of the “cycling” process in an aquarium, so let’s touch on that for just a moment! 

During the "cycling" process, ammonia levels will build and then suddenly decline as the nitrite-forming bacteria multiply in the system. Because nitrate-forming bacteria don't appear until nitrite is available in sufficient quantities to sustain them, nitrite levels climb dramatically as the ammonia is converted, and keep rising as the constantly-available ammonia is converted to nitrite.

Once the nitrate-forming bacteria multiply in sufficient numbers, nitrite levels decrease dramatically, nitrate levels rise, and the tank is considered “fully cycled.”

And of course, the process of creating and establishing your aquariums ecology doesn't end there.

With a stabilized nitrogen cycle in place, the real "evolution" of the aquarium begins. This process is constant, and the actions of Nature in our aquariums facilitate changes. 

And our botanical-method systems change constantly.

They change over time in very noticeable ways, as the leaves and botanicals break down and change shape and form. The water will darken. Often, there may be an almost "patina" or haziness to the water along with the tint- the result of dissolving botanical material and perhaps a "bloom" of microorganisms which consume them. 

This is perfectly analogous to what you see in the natural habitats of the fishes that we love so much. As the materials present in the flooded forests, ponds, and streams break down, they alter it biologically, chemically, and even physically. 

It's something that we as aquarists have to accept in our tanks, which is not always easy for us, right? Decomposition, detritus, biofilms- all that stuff looks, well- different than what we've been told over the years is "proper" for an aquarium. And, it's as much a perception issue as it is a husbandry one.  I mean, we're talking about materials from decomposing botanicals and wood, as opposed to uneaten food, fish waste, and such.

What's really cool about this is that, in our community, we aren't seeing hobbyists freak out over some of the aesthetics previously associated with "dirty!" 

It's seen as a fundamental part of the evolution of the tank.

And soon, you'll see the emergence of elegant, yet simple life forms, such as bacterial biofilms and fungal growths. We've long maintained that the appearance of biofilms and fungi on your botanicals and wood are to be celebrated- not feared. They represent a burgeoning emergence of life -albeit in one of its lowest and (to some) most unpleasant-looking forms- and that's a really big deal. 

Biofilms, as we've discussed ad nauseam here, 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. 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.

Tannin's creative Director, Johnny Ciotti, calls this period of time when the biofilms emerge, and your tank starts coming alive "The Bloom"- a most appropriate term, and one that conjures up a beautiful image of Nature unfolding in our aquariums- your miniature aquatic ecosystem blossoming before your very eyes!

The real positive takeaway here:

Biofilms and fungal growths are really a sign that things are working right in your aquarium! A visual indicator that natural processes are at work, helping forge your tank's ecosystem.

About a year ago, had a discussion with our friend, Alex Franqui. His beautiful Igarape-themed aquarium pictured above, "bloomed" beautifully, with the biofilms, fungal growths, and sediments working together to create a stunning, very natural functioning- and appearing-ecosystem. He was not repulsed at all. Rather, he was awed and fascinated...He celebrated what was occurring in his tan. He has an innate understanding of the ecological process, and replaced "fear and loathing" with excitement.

Alex is a hardcore aquascaper, and to see him marveling and rejoicing in the "bloom" of biofilms in his tank is remarkable.

He gets it.

And it turns out that our love of biofilms is truly shared by some people who really appreciate them as food...Shrimp hobbyists! Yup, these people (you know who you are!) go out of their way to cultivate and embrace biofilms and fungi as a food source for their shrimp. 


They get it.

And this makes perfect sense, because they are abundant in Nature, particularly in habitats where shrimp naturally occur, which are typically filled with botanical materials, fallen tree trunks, and decomposing leaves...a perfect haunt for biofilm and fungal growth! 

Nature celebrates "The Bloom", too.

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

Time for a little thought experiment...

You're a fish.

Seriously. Make yourself a fish...for a second. (I think I'd be a Black Ghost Knife, FYI. What, you thought I'd be a Cardinal Tetra or something? Really? Sheesh!)

Your main goals in life are avoiding predators, finding food, and reproducing. The "finding food" part is what we're focusing on in this experiment.

Now, back to being you for a second.

Would you like to move into a house which didn’t have a refrigerator full of food?  I wouldn’t, for sure. Unlike humans, fishes seem to have not lost their "genetic programming" for grazing and hunting for food. Let’s face it—most of the waking hours of aquatic animals are devoted to acquiring food and reproducing. They need to have some food sources available to "hunt and graze" for.

That’s reality.

So why not help accommodate our your animals’ needs by supplementing their prepared diet with some “pre-stocked” natural foods in their new home? You know, slow down, get things "going" a bit, and then add the fishes?

I’m not talking about tossing in a few frozen brine shrimp hours before the first fishes go in the tank—I’m talking about a deliberate, systematic attempt to cultivate some living food sources within the system before a fish ever hits the water! Imagine a “new” system offering numerous foraging opportunities for its new inhabitants!

in our world, that might mean allowing some breakdown of the botanicals, or time for wood or other botanicals to recruit some biofilms, fungi- even turf algae on their surfaces before adding the fishes to the aquarium. 

“Scott. You’re being impractical here! It could take months to accomplish this. I’ve just spent tons of money and time setting up this tank and you want me to deliberately keep this tank devoid of fishes while the biofilms form and Daphnia reproduce?”

Yes. Seriously.

 I am a bit crazy. I’ll give you that. 

Yet, with my last few systems, this is exactly what I did. 


Well, for one thing, it creates a habitat for sighs which is uniquely suited to their needs in a different way.

Think abut the way most fishes live. They spend a large part of their existence foraging for food. Even in the cozy, comfortable confines of the aquarium.

So, why not create conditions for them which help accommodate this instinctive behavior, and provide opportunities for supplemental (or primary!) nutrition to be available to them by foraging.

Now, I have no illusions about this idea of "pre-stocking" being a bit challenging to execute.

I’m no genius, trust me. I don’t have half the skills many of you do but I have succeeded with many delicate “hard-to-feed” fishes over my hobby “career.” 

Any "secret" to this?

None at all.  I'm simply really fucking patient.

Success in this arena  is simply a result of deploying..."radical patience."  The practice of just moving really slowly and carefully when adding fishes to new tanks. 

A really simple concept.

I mean, to some extent, we already deploy this practice with our botanical-method tanks, right? The very process of creating a botanical-method aquarium lends itself to this "on board supplemental food production" concept. A concept that's pretty analogous to what occurs in Nature, right?


And one of the most important functions of many botanically-influenced wild habitats is the support of food webs. As we've discussed before in this blog, the leaf litter zones in tropical waters are home to a remarkable diversity of life, ranging from microbial to fungal, as well as crustaceans and insects...oh, and fishes, too!  These life forms are the basis of complex and dynamic food webs, which are one key to the productivity of these habitats.

You can do this. You can foster such a "food web"- or the basis for one- in your aquarium!

Wait a minimum of three weeks—and even up to a month or two if you can stand it, and you will have a surprisingly large population of micro and macro fauna upon which your fishes can forage between feedings.

Having a “pre-stocked” system helps reduce a considerable amount of stress for new inhabitants, particularly for wild fishes, or fishes that have reputations as “delicate” feeders.

And think about it for a second.

This is really a natural analog of sorts. Fishes that live in inundated forest floors (yeah, the igapo again!) return to these areas to "follow the food" once they flood. In fact, other than the physical flooding itself, this pursuit of food sources is the key factor in the migration of fishes into these habitats.

So, what would some candidate organisms be for "pre-stocking" a botanical-style aquarium?

How about starting with (okay, sounding a bit commercial, I know, but...) the versatile Purple Non Sulphur Bacteria (PNSB), Rhodopseudomonas palustris- the species which forms our product, "Culture." PNSB are useful for their ability to carry out a particularly unusual mode of metabolism: "anaerobic photoheterotrophy."

In this process, they consume organic wastes while inhabiting moderately illuminated and poorly oxygenated microhabitats (patches of detritus, leaf litter beds, shallow depths of substrate, deeper pores of expanded clay media, etc.). In addition to helping to maintain an ecologically stable microhabitat, "Culture" provides a nutritious live food source for zooplankton as well as soil mesofauna.

Yeah, these guys form the "foundation" of your food chain! (And yeah, we'll have "Culture" back in stock soon...we're re-thinking the packaging to make the product more affordable!)

Next, perhaps some "starter cultures" of organisms like Paramecium, Euglena, etc. You know, "infusoria" from the old school aquarium literature. And then, small crustaceans like Daphnia, and copepods of various types.



Pure cultures of all of these organisms are available online from various biological supply houses. They're a fantastic source of biodiversity for your aquarium! 

Of course, the more daring among you may want to introduce various worms, like "Black Worms" or Tubifex worms, if you can find clean cultures of them. For that matter, even "blood worms", which are actually the larval phase of the midge.

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

These organisms, in turn, become part of the diet for many fishes.

Food Web.

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

It performs the same function in an aquarium- if we allow it to.

And of course, if you observe the behavior of many of your fishes in the aquarium, such as characins, cyprinids, Loricariids, and others, you'll see that, in between feedings, they'll spend an awful lot of time picking at "stuff" on the bottom of the tank. In a botanical method aquarium, this is a pretty common occurrence, and I believe an important benefit of this type of system. 

When you start seeing your fishes "graze" casually on the materials that pop up on your driftwood and botanicals, you start realizing that, although it might not look like the aesthetics we have had in mind in years past, it is a beautiful thing to our fishes!

 You can do this.

Remember, it's all part of the game with a botanical-influenced aquarium. Understanding, accepting, and celebrating "The Bloom" is all part of that "mental shift" towards accepting and appreciating a more truly natural-looking, natural-functioning aquarium.

The "price of admission", if you will- along with the tinted water, decomposing leaves, etc., the metaphorical "dues" you pay, which ultimately go hand-in-hand with the envious "ohhs and ahhs" of other hobbyists who admire your completed aquarium when they see it for the first time.

Stay studious. Stay diligent. Stay observant. Stay patient...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Your fishes call it "food..."

If you've followed us for any length of time, you're well aware that we are not just pushing you to play with natural, botanical-method aquariums only for the pretty aesthetics.

I mean, yeah, they look awesome, but there is so much more to it than that. We are unapologetically obsessed with the function of these aquariums and the wild habitats which they attempt to represent!

And one of the most important functions of many botanically-influenced wild habitats is the support of what ecologists call food webs-a system of interlocking and interdependent food other words, "what eats what" in the aquatic ecosystem!

It's a fascinating field of study that plays beautifully into what we do in our botanical method aquariums.

As we've discussed before, the leaf litter zones in tropical waters are home to a remarkable diversity of life, ranging from microbial to fungal, as well as crustaceans and insects...oh, and fishes, too!  These life forms are the basis of complex and dynamic food webs, which are one key to the ecological "productivity" of these habitats.

By researching, developing, and managing our own botanically-influenced aquaria, particularly those with leaf litter beds, we may be on the cusp of finding new ways to create "nurseries" for the rearing of many fishes!

At least upon superficial examination, our aquarium leaf litter/botanical beds seem to function much like their wild counterparts, creating an extremely rich "microhabitat" within our aquariums. And initial reports form those of you who breed and rear fishes in your intentionally "botanically-stocked" aquariums are that you're seeing great color, more regularity in spawns, and higher survival rates from some species.

I don't believe that this is mere coincidence.

We're just beginning here, and the future is wild open for huge hobbyist-level contributions that can lead to some serious breakthroughs in understanding how food webs develop in aquariums! 

Maybe we will finally overcome generations of fear over detritus and fungi and biofilms- the life-forms and "by-products" which literally "power" the aquatic ecosystems we strive to duplicate in our aquariums.

There is something tantalizing to me about the idea of our fishes being able to supplement what we feed them by foraging in the aquarium. To some extent, virtually every aquairum has some microorganisms, algae, etc. which fishes can "snack on" in between our feedings. Yet, botanical-method aquariums, with their abundance of decomposing leaves and the ecology which they foster, take this to a whole different level.

I'm particularly fascinated with the idea of the fry of our fishes being able to sustain themselves or supplement their diets substantially, with what is produced inside the little habitat we've created in our tanks! A botanical method aquarium is, I believe, an ideal "nursery" for many species of fishes to begin their lives, and the experience of many of my fish-breeding friends who have played with this idea successfully helps to prove my thesis.


Let's consider some of the types of food sources that our fishes might utilize in the wild habitats that we try so hard to replicate in our aquariums, and perhaps develop a greater appreciation for them when they appear in our tanks. Perhaps we will even attempt to foster and utilize them to our fishes' benefits in unique ways?

One of the important food resources in natural aquatic systems are what are known as macrophytes- aquatic plants- which grow in and around the water, emerged, submerged, floating, etc. Not only do macrophytes contribute to the physical structure and spatial organization of the water bodies they inhabit, they are primary contributors to the overall biological stability of the habitat, conditioning the physical parameters of the water. Of course, anyone who keeps a planted aquarium could attest to that, right? 


One of the interesting things about macrophytes is that, although there are a lot of fishes which feed directly upon them, in this context, the plants themselves are perhaps most valuable as a microhabitat for algae, zooplankton, and other organisms which fishes feed on. Small aquatic crustaceans seek out the shelter of plants for both the food resources they provide (i.e.; zooplankton, diatoms) and for protection from predators (yeah, the fishes!).

I have personally set up a couple of systems recently to play with this idea- botanical-influenced planted aquariums, and have experimented with going extended periods of time without feeding my fishes who lived in these tanks- and they have remained as fat and happy as when they were added to the tanks…

Something is there- literally!  

Perhaps most interesting to us botanical-method aquarium people are epiphytes. These are organisms which grow on the surface of plants or other substrates and derive their nutrients from the surrounding environment. They are important in the nutrient cycling and uptake in both nature and the aquarium, adding to the biodiversity, and serving as an important food source for many species of fishes.

In the case of our aquatic habitats, like streams, ponds, and inundated forests, epiphytes are abundant, and many fishes will spend large amounts of time foraging the biocover on tree trunks, branches, leaves, and other botanical materials. Although most animals use leaves and tree branches for shelter and not directly as a food item, grazing on this epiphytic growth is very important.

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

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

And of course, if you observe the behavior of many of your fishes in the aquarium, such as characins, cyprinids, Loricarids, and others, you'll see that in between feedings, they'll spend an awful lot of time picking at "stuff" on the bottom of the tank. In a botanical style aquarium, this is a pretty common occurrence, and I believe an important benefit of this type of system. 

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

Just like in Nature. 


It's well known by scientists that in many habitats, like inundated forest floors, etc., fishes will adjust their feeding strategies to utilize the available food sources at different times of the year, such as the "dry season", etc. And it's also known that many fish fry feed actively on bacteria and fungi in these I suggest once again that a botanical method aquarium could be an excellent sort of "nursery" for many fish species! 


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


And then, of course, there's the “allochthonous input” that we’ve talked about so much: Foods from the surrounding environment, such as flowers, fruits, terrestrial insects, etc. These are extremely important foods for many fish species that live in these habitats. We mimic this process when we feed our fishes prepared foods, as stuff literally "rains from the sky!" Now, I think that what we feed to our fishes directly in this fashion is equally as important as how it's fed.

I'd like to see much more experimentation with foods like live ants, fruit flies, and other winged insects. Of course, I can hear the protests already: "Not in MY house, Fellman!" I get it. I mean, who wants a plague of winged insects getting loose in their suburban home because of some aquarium feeding experiment gone awry, right?

That likely wouldn't go over well with just about any significant other in the "non-aquarium" world, right?

That being said, I would encourage some experimentation with ants and the already fairly common wingless fruit flies. Sure, you can just catch some ants outside and drop them into your tank...or you could culture them...Remember those "Ant Farms" that some of us had when we were kids?

Can you imagine one day recommending an "Ant Farm" as a piece of essential aquarium food culturing equipment? It's at least as wacky as culturing peanut beetle larvae or microworms, and not nearly as messy!

Why not, right? 😆

And of course, easier yet- we can simply foster the growth of potential food sources that don't fly or crawl around- they just arise when botanicals and wood and stuff meet water...We just need to not wipe them out as soon as they appear! Damn, using the collection and feeding of winged insects as an opposite example sure makes fungal growths and biofilms more palatable, right?

As many of you may know, I've often been sort of amused by the panic that many non-botanical-style-aquarium-loving hobbyists express when a new piece of driftwood is submerged in the aquarium, often resulting in an accumulation of fungi and biofilm.

I realize this stuff can look pretty shitty to many of you, particularly when you're trying to set up a super-cool, "sterile high-concept" aquascaped tank.

That being said, I think we need to let ourselves embrace this stuff and celebrate it for what it is: Life. Sustenance. Diversity. Foraging.

I think that those of us who maintain botanical method aquariums have made the "mental shift" to understand, accept, and even celebrate the appearance of this stuff.

We learn to appreciate it by looking to Nature.

Natural habitats are absolutely filled with this every nook and cranny. On every rock, branch, seed pod, and leaf. It's like the whole game here- an explosion of life-giving materials, free for the taking...

A priceless natural resource.

It's why, a long time ago, I learned to not be put off by the mere appearance of these life forms when they showed up in my early botanical method aquariums. They are literally the drivers of underwater ecology- a priceless resource which Nature happily deposits into our aquariums. 

A true gift from Nature. 

Yet, for a century or so in the hobby, our first instinct is to reach for the algae scraper or siphon hose, and lament our misfortune with our friends.

It need not be this way. Its appearance in our tanks is a blessing. 


You call it "mess." I call it a blessing.  Your fishes call it “food."

Another "mental shift", I which many of you have already made, no doubt. Or, I hope you have..or can.

The ability to appreciate this stuff- to move beyond the fear, loathing, and disdain which many hobbyists have for it-is to truly grow as a hobbyist. In fact, the oft-quoted, absurdly mis-interpreted and applied (to the point where it's almost a mockery) statement by none other than the late Akashi Amano that, "To know Mother Nature is to love her smallest creations..." sums this up perfectly. 

Yeah, he got it. 

You can, too. 

Now look, I'm not saying that your tank has to be packed with biofilms, fungal growth, decomposing leaves, and detritus in order to provide all of these benefits to your fishes. However, I am suggesting that, as hobbyists, we should to allow some amount of this material to accumulate in our tanks.

Remember, the presence of these materials does not signify some "problem" with your aquarium, as is so easy to conclude. 

Rather, their presence indicates that your aquarium is functioning very much like a natural aquatic ecosystem. That it's doing what Nature has done for eons. To disrupt the process by aggressively siphoning out every gram of detritus, scraping off every bit of fungal growth or biofilm actually inhibits or even completely disrupts processes which can benefit your tank in manifold ways.

Not only do fungal growths and biofilms serve as a supplemental food resource for our fishes, they help "filter" the water by processing nutrients. And a large part of their "fuel" is the leaf litter, seed pods, wood, and the detritus which occurs as a result of their decomposition. 

 Yeah, we talk about this a lot around here, I know. 

However, it's such an important part of our philosophy and methodology that it cannot be stated often enough. 

And the sooner we embrace this stuff, the sooner we begin to realize the lasting benefits that it can bring to our aquariums!

Stay confident. Stay bold. Stay curious. Stay diligent. Stay studious...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Heading to the bottom...Again!

Time to hit on another of my fave topics regarding botanical method aquariums; one that we've talked about before- yet one that is still new and exciting to many of us, and perhaps clouded at times with a lot of misinformation, too.

We're talking about botanically-supplemented substrates!

For far too long in the aquarium hobby, I think that we've treated aquairum substrates as simply an afterthought. I mean, there are all sorts of sands and gravels on the market today, but I think that we sort of take them for granted- or at the very least, we treat them as a "requirement" when setting up a tank, and move on to other, more "exciting stuff": "Sand added, check. Time to select the wood!"

That sort of thing.

One of the most "liberating" things we've seen in the botanical-method aquarium niche is our practice of utilizing the bottom itself to become a feature aesthetic point in our aquariums, as well as a functional mechanism for the inhabitants.

"Oh, shit, he's talking about that 'functional aesthetic' thing again!"

Yeah. Yes I am. 😎

Because I think that there are a lot of "missed opportunities" to do something cool with substrates in our tanks. Opportunities to make it a much more important part of the aquarium. 

When you look at it from our rather biased perspective, and from a strictly aesthetic sense, the bottom itself becomes a big part of the aesthetic appeal of the aquarium. You may not focus on it, observationally, but it's hugely important. And of course, I see the bottom of the aquarium as more than just sand or whatever. Rather, it's a important component of the aquarium habitat, with the botanical materials placed upon or mixed into the substrate- or, in some cases, becoming the substrate!

These materials form an attractive, texturally varied "microscape" of their own, creating color and interest. In addition to be being comprised of the usual sands and gravels, we can be adding bits of botanicals, root pieces, twigs, leaves, etc. into the mix.


Again, the focus isn't just on aesthetics. 

It's about creating a habitat for the fauna which help "run" our tanks!

Much like in Nature, the materials that we place on the bottom of the aquarium will become an active, integral part of the ecosystem. From a "functional" standpoint, bottoms comprised of 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.

So, the idea of creating rich, diverse botanical-influenced substrates for the purpose of infusing tannins, humic substances, and other compounds- as well as creating a "matrix" for the growth and propagation of beneficial micro and microfauna is pretty appealing to me.

Using a botanically-infused substrate to create a unique, ecologically diverse, functional, and aesthetically interesting affect on the aquarium- even one that doesn't have aquatic plants in it- is a sort of different approach.

Functionality. Interest. Aesthetics. Stability. They're all there!


Nature provides no shortage of features which can provide inspiration for unique aquariums.

Think about the materials which accumulate on and in the substrates of natural aquatic habitats, and why they accumulate in the first place. Well, typically, in addition to soils and leaves, you'll see sediments, pieces of plant roots, bits of twigs and bark, and the occasional seed pod. Almost all of this material arrives in these bodies of water from the surrounding terrestrial environment.

Some of it is present on forest floors, and when nearby streams overflow, inundating the once dry floor, these materials become part of the aquatic environment, influencing both the structure and the ecology of the habitat. Other materials, like sediments, are the product of hydrology and erosion- rocks ground down over eons by water; or soils- which find their way into streams during periods of intense rain, with the resulting material distributed over vast distances by current.

The beauty of Nature is that She uses pretty much everything that is thrown at Her. Fishes and other organisms feed directly upon some of this material, or on the other life forms (small crustaceans, insects, fungal growths) which live among it. The bottom of streams and other becomes a vibrant, ecologically diverse habitat, which supports a tremendous amount of life at many levels.

And we just throw bag of aquarium sand or gravel on the bottom of our tanks...and move on!

Shit. Really?

Like, WTF is a matter with us fish geeks? There is HUGE opportunity here! We need to give a lot more thought to what goes on the bottom of our aquariums! Instead of becoming a literal "placeholder" in our tanks, substrate should become the ecological "backbone"- and a (functionally aesthetic) foundation of our miniature aquatic ecosystems- just like it is in Nature!

Now, the first "pushback" we hear from critics of this type of approach in aquariums is that it will result in all sorts of problems- ranging from suppressed pH to high levels of nitrates, or even pockets of hydrogen sulfide and other nasty stuff accumulating.

I think that this is an incredible over-reaction and grounded in not fully thinking through why we are creating substrates like this in the first place.

In Nature, the leaf litter "community" of fishes, insects, fungi, and microorganisms is really important to the overall tropical environment, as it assimilates terrestrial material into the blackwater aquatic system (and, by doing this, acts to reduce the loss of nutrients to the forest which would inevitably occur if all the material which fell into the streams was washed downstream...)

The key point: These materials foster the development of life forms which process it. Stuff is being used by life forms.

It's the same in our aquariums.

And bits of botanical materials and such not only provide a physical substrate upon which these organisms can grow and multiply as they process it- they provide a sort of "on board nutrient processing center" within the aquarium.

If you approach this "substrate enrichment" idea holistically, rather than just from some warped aesthetic mindset, creating and managing such a system is not at all difficult or dangerous. In fact, you don't really need to give it all that much thought in a well-managed aquarium, once it's set up.

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, sediment, bark, and other botanical materials is the "buildup of hydrogen sulfide", CO2, and other undesirable compounds within the substrate.

Well, sure, I can't entirely "diss" fellow hobbyists for having this fear. It does make sense that if you have a large amount of decomposing material in an aquarium, then some of these compounds are likely to accumulate in heavily-"active" substrates. The big "bogeyman" that we all seem to zero in on in our "sum of all fears" scenarios - the one which keyboard warriors on the forums will pounce on- is an accumulation of deadly 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 really "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? Are we managing tanks in such a way as to encourage no circulation whatsoever?

I think that we're more likely to see some oxygen in this layer of materials, and in fact, 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-method 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 aquarium-standard 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 method 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.

Yeah- in my experience, based on literally a lifetime of playing with all sorts of combinations of materials in dozens and dozens of my aquariums' substrates ('cause I've always been into that stuff!), I cannot attribute a single environmental lapse, let alone, a "tank crash", as a result of such additions.

A well-managed substrate, in which uneaten food and fish feces are not allowed to accumulate to excess, and in which regular nutrient export processes are embraced, rather than decimated by constant interference (ie; siphoning) it's not an issue, IMHO. When other good practices of aquarium husbandry (ie; not overcrowding, overfeeding, etc.) are empIoyed, a botanically-"enriched" substrate can enhance- not inhibit- the nutrient processing within your aquarium and help maintain high water quality for extended periods of time.

Like many of you, I have always been a firm believer in some forms of nutrient export being employed in every single tank I maintain. Typically, it's regular water exchanges. Not "when I think about it', or "periodically", mind you.

Nope, it's weekly. 

Now look,  I'm not saying that you can essentially disobey all the common sense husbandry practices we've come to know and love in the hobby (like not overcrowding/overfeeding, etc.) and just change the water weekly and everything's good. And I'm not suggesting that the only way to succeed with adding botanical materials to the substrate is to employ massive effort at nutrient export; the system otherwise teetering on a knife's edge, with disaster on one side and success on the other. 

It's not that binary. 

Our aquariums are more resilient than that. If we set them up to be. Common sense aquarium management, with an eye towards how natural aquatic systems work, is key, IMHO.

Of course, an aquarium is NOT a stream, river, etc. However, the same processes and "rules" imposed by Nature that govern the function of these wild ecosystems apply to our little glass and acrylic boxes. It's simply a matter of nuance in management and understanding how these wild habitats work on a basic level.

I'd love to keep us in the mindset of thinking about our aquariums as little "microcosms", not just "aquatic dioramas."

Think about this: The idea of a substrate "enriched" with botanical materials is completely in line with the practices of a "dirted" planted aquarium. In our case, not only will there be an abundance of material for microorganisms and crustaceans to forage and multiply among, trace elements and essential plant nutrients will also be present in such a substrate. And, of course there will be the constant addition of tannins and humic substances into the water,  which provide many known benefits for fishes as well.

The best of both worlds, I think.

Again, it's not about creating a cool Instagram-ready "look."

It's about trying to create an entire aquatic ecosystem.

Embracing and fostering not just the look, but the very processes and functions which take place in natural aquatic systems. Is it as simple as crushing some leaves, adding some coconut-based material, covering it up with sand and you have an "instant tropical stream?" No, of course not. There is no such "magic bullet!" You need to look at things sort of "holistically"- with an eye towards nutrient export and long-term maintenance. 

For those of you who are adventurous, experimental, diligent, and otherwise engaged with managing and observing your aquariums, I think this process offers amazing possibilities. Not only will you gain some fascinating insights and the benefits of "on-board" nutrient export/environmental "enrichment"- you will also get the aesthetics of a more natural-looking substrate as well. (Let's face it, no matter how "function first" we feel that we are, everyone likes a nice-looking aquarium, right?)


So, the best way to "enrich" (for want of a better term) your substrate is to add the  botanical materials and sediments before you fill the tank up with water. In the case of leaves, bits of botanicals, etc., you'd want to have boiled/steeped them previously, so that they are rid of any surface contaminants, and to assure that their tissues are saturated enough to get them to sink immediately upon submersion.

There is no set "process" for this, other than to mix these materials into the upper layers of substrate as you add them. You will just sort of know when you've achieved the look and texture that pleases you (that's the "aesthetic" part!), and take comfort in knowing that just about any amount of these materials that you're adding to your system will help accomplish the "functional" aspect.

Once your substrate is in place, Nature takes over and the materials develop that lovely "patina" of fugal growth, biofilms and microbial colonization, 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!

 At this point, I have to admit that there are many hobbyists who will never find any sort of appeal whatsoever in a botanically-enriched substrate, dark and complex, filled with all sorts of "stuff" besides just sand. The so-called "Nature Aquarium" cult crowd, or the truly "artistic" aquascaping people, for example, will likely never approve of this idea, because it looks "dirty" to them, and because some of the aesthetic and management "work" is being "ceded" to Nature. They need to be in control.

I admit, 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.

From a maintenance standpoint, it's pretty straightforward. You monitor your environmental parameters regularly, and conduct routine water exchanges, taking care not to siphon aggressively from the substrate. You simply don't want to disrupt the very processes within the substrate that you're trying to foster. And trust me, your fishes will spend a lot of time foraging among it.

Much like what occurs spontaneously in Nature, the materials that we deliberately place on the bottom of the aquarium will become an active, integral part of the ecosystem

Like so many things we discuss here, I admit that simply don't have all the answers about every aspect of botanically-supplemented substrates. There is a ton to learn! That's part of the joy of this process- sort of figuring out why and how it works as you're enjoying the success!

Playing with ideas like botanically supplemented substrates truly pushes the boundaries between what we do al the time in the hobby, and those outer regions where few have tread before. There will be challenges, discoveries..and rewards for taking this road less travelled.

And that's part of the fun, isn't it?

Stay creative. Stay brave. Stay curious. Stay diligent...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Specialized diets, "Leopard Frogs", and re-thinking assumptions...

I'm fascinated by the dietary preferences of fishes. How they've evolved over eons to consume various items found in their environments; how many fishes became "specialists" as an adaptation to the habitats in which they live.

And, as an aquarist who derives great pleasure from seeing his fishes "live off the land" and consume foods from the aquarium environment in which they reside, I really find some of the seunderlying feeding strategies fascinating. One of the more interesting examples is the consumption of wood by various species of fishes.

We read a lot about fishes which eat wood and wood-like materials.

Of course, the ones that come immediately to mind are the Loricariidae, specifically, Panaque species. Now, I admittedly am the last guy who should be authoritatively discussing the care of catfishes, having maintained maybe a couple dozen or so species during a lifetime of aquarium keeping. However, I do understand a little bit about their diets and the idea of utilizing wood- and botanical materials- in the aquarium for the purpose of supplementing our fishes' diets!

And of course, I'm equally fascinated by the world of biofilms, decomposition, microorganism growth and detritus...And this stuff plays right into that! 

Now, the idea of xylophagy (the consumption and digestion of wood) is of course, a pretty cool and interesting adaptation to the environment from which these fishes come from. And as you'd suspect, the way that wood is consumed and digested by these fishes is equally cool and fascinating! 

It's thought by ichthyologists that the scraping teeth and highly angled jaws of the Loricariidae are a perfect adaptation to this feeding habit of "scraping" wood. And of course, it's even argued among scientists that these fishes may or may not actually digest the wood they consume! While scientists have identified a symbiotic bacteria which is found in the gut of these fishes that helps break down wood components, it's been argued by some the the fishes don't actually digest and metabolize the wood; indeed deriving very little energy from the wood they consume!


In fact, a lab study by Donovan P. German was described in the November, 2009 Journal of Comparative Physiology, in which several species were fed wood and found to actually digest it quite poorly

" laboratory feeding trials, (Pterygoplichthys cf. nigrolineatus and Hypostomus pyrineusi)  lost weight when consuming wood, and passed stained wood through their digestive tracts in less than 4 hours. Furthermore, no selective retention of small particles was observed in either species in any region of the gut. Collectively, these results corroborate digestive enzyme activity profiles and gastrointestinal fermentation levels in the fishes’ GI tracts, suggesting that the wood-eating catfishes are not true xylivores such as beavers and termites, but rather, are detritivores like so many other fishes from the family Loricariidae."

Did you see that? Detritioves. Like, they're taking in wood to get other stuff out of the deal... And detritus is comprised of stuff like macrophytes, algae, and particulate organic carbon.


And this little nugget from the same study:  "...The fishes consumed 2–5% of their body mass (on a wet weight basis) in wood per day, but were not thriving on it, as Pt. nigrolineatus lost 1.8 ± 0.15% of their body mass over the course of the experiment, and Pt. disjunctivus lost 8.4 ± 0.81% of their body mass.

Oh, that's weird.

Yet, anatomical studies of these fishes showed that the so-called "wood-eating catfishes" had what physiologists refer to as "body size-corrected intestinal lengths" that were 35% shorter than the detritivore species. What does this mean? Could they have perhaps had at one time- and subsequently lost- their ability to digest wood?



And to make it even weirder, check out this passage from a study by Lujan, Winemiller, and Armbruster:

"Loricariids have a dense endoskeleton and are covered with dermal plates composed primarily of calcium phosphate, giving them a high physiological demand for dietary phosphorus. Paradoxically, the rivers and streams inhabited by loricariids as well as the detritus and biofilm that most loricariids consume tend to be highly Phosporus deficient."

The same study noted that, "Loricariids as a whole are largely unable to digest lignocellulose, and instead derive most nutrients and energy from easily digestible breakdown products (e.g., disaccharides and dipeptides) that are produced during microbial degradation of submerged, decomposing wood."

Oh, interesting!

I think it's yet another case of us as hobbyists drawing innocent conclusions based on anecdotal or superficial observations. I mean,"... they're munching on my wood, therefore, they must be 'eating' it!"


Now, to the point of the argument that most loricariids are primarily detritivores, consuming a matrix of biofilm, algal growth, microorganisms, and (for want of a better word) "dirt"- what does this mean to us as hobbyists? Well, for one thing, this has made them remarkably adaptable fishes in the aquarium. They will definitely rasp at wood", but according to the studies I just cited, they are not "eating" it, per se.

Now, my personal experience with Loricariidae is nothing like many of yours, and an observation I've made over the years is at best anecdotal- but interesting:

If you follow "The Tint", you know I've had a years-long love affair with Peckolotia compta aka "L134 Leopard Frog"- a beautiful little fish that is filled with charms. Well, I recall, are years back, that my first specimen seemed to have vanished into the ether following a re-configuration/rescape of my home blackwater/botanical-method aquarium. I thought somehow I either lost the fish during the re-scape, or it died and subsequently decayed without my detecting it... Pretty upsetting either way, but I couldn't find any trace of it!

For almost three months, the fish was M.I.A., just....gone.

And then one, day- there she was, poking out from the "Spider Wood" thicket that formed the basis of my newer hardscape! To say I was overjoyed was a bit of an understatement, of course! And after her re-appearance, she was out every day. She looked just as fat and happy as when I last saw her in the other 'scape...which begs the question (besides my curiosity about how she evaded detection)- What the fuck was she feeding on during this time?

Well, I suppose it's possible that some bits of frozen food (I fed frozen almost exclusively at that time) got away from my population of hungry characins and fell to the bottom...However, I'm pretty fastidious- and the other fishes (characins) were voracious mid-water-column feeders! To think that any appreciable amount got away from the hungry hoard was a bit hopeful. I believed at the time (and now am fully convinced) that it was more likely the biofilms, fungal growth, and perhaps some of the compounds from surface tissues of the "Spider Wood" I used in the hardscape that she was feeding on.

"Spiderwood" (aka Azalea root) stuff does recruit significant biological growth on it's surfaces when submerged , and curiously, in this tank, I noticed that, during the first few months, the wood seemed to never accumulate as much of this stuff as I had seen it do in past tanks which incorporated it!

I attributed this to perhaps some feeding by a population of Nanostomus eques, which have shown repeatedly in the past to feed on the biofilm or "aufwuchs" accumulating on the wood.

I'm sure that was a valid observation, but they were actively taking prepared foods as the bulk of their diet, so I have a hard time that they solely were responsible. 

There was also a layer of Live Oak leaves distributed throughout the booth of the wood matrix, which, although they break down very slowly compared to other leaves we use, DO ultimately soften over time and break down over time. Since they are rather "durable", they do accumulate a lot of fungal growth and biofilms on their surfaces.

Interestingly, in this tank, I was finding little tiny amounts of very broken-down leaves, which I attributed to decomposition, but thinking back on it, looks more like the end product of "digestion" by someone!

I don't think I ever saw my L134 consuming prepared food. When I did observe her activities, she was seemingly "grazing" away at the wood surfaces and on botanicals...That's all the proof that I needed to confirm my theory that she's pretty much 100% detritivorous, and that the botanical-method aquariums she's resided in provide a sufficient amount of this material for her to consume.

To this day, I've never seen her eat prepared foods!

I have since acquired three captive-bred specimens from my friend, master breeder Sumer Tiwari, and this group has been seen to take prepared food on occasion. At the very least, adding some pellets or frozen foods seems to initial some kind of response in the fish, wether they appear to eat it or not.

So, back the the whole "xylophore thing"... After reading the studies I mentioned, I think that in the aquarium, as well as in the wild, much of what we think is actually "consumption" of the wood by the fishes is simply incidental- as in, the fishes are trying to eat the biocover and detritus on the surface tissues of the wood, and perhaps obtain some nutrition from the compounds contained in the softer portions of the wood. They apparently do a pretty good job (with their specialized mouthparts) of rasping away the surface tissues of the wood!

So, yeah- apparently, some of the wood may pass through the digestive tract of the catfishes, but it's passed without metabolizing much from it...perhaps like the way chickens  consume gravel, or whatever (don't they? City boy here! WTF do I know about chickens!)...or the way some marine Centropyge angelfishes "nibble" on corals in their pursuit of algae, detritus, and biofilms.

Again, my perusal of German's scientific paper seems to support this theory:

"Catfishes supplement their wood diet with protein-rich detritus, or even some animal material to meet their nitrogen requirements. Although I did not observe animal material in the wood-eating catfish guts, Pt. disjunctivus did consume some animal material (including insects parts, molluscs, and worms), and all three species consumed detritus."

And finally, the "clincher", IMHO: "The low wood fiber assimilation efficiencies in the catfishes are highly indicative that they cannot subsist on a wood only diet."



I mean, it's just one paper, but when he's talking about isotopic tracing of materials not consistent with digestion of wood in the guts of Loricariids, I think that pretty much puts the "eats wood" thing to bed, right? His further mention that, although some cellulose and lignin (a component of wood and our beloved botanicals!) was detected in the fish's fecal material, it was likely an artifact of the analysis method as opposed to proof that the fishes derived significant nutrition from it.

So what does all of this stuff mean to us? 

Well, for one thing, once again- detritus/biofilm/fungal growths = good. Don't loathe them. Love them.

Your fishes apparently do.

I think it means that, as hobbyists probably knew, theorized, and discussed for a long time- that the Loricariids consume detritus, biofilms, and prepared foods when available. This is not exactly earth-shattering or new.

However, I think understanding that our botanical-method aquariums can- and do- provide a large amount of materials from which which these and other fishes can derive significant nutrition furthers my assertion that this type of system is perfect for rearing and maintain a lot of specialized feeders. 

Materials like the harder-"shelled" botanicals (ie; "Skyfruit" pods, Cariniana pods, Mokha pods, bark, etc.) tend to recruit significant fungal growths and biofilms, and accumulate detritus in and on their surfaces. And of course, as they soften, some fishes apparently rasp and "consume" some of them directly, likely passing most of it though their digestive systems as outlined in the cited study, extracting whatever nutrition is available to them as a result. This is likely the case with leaves and softer botanicals as well.

Incidental consumption.

The softer materials might also be directly consumed by many fishes, although the nutrition may or may not be significant. However, the detritus, fungal, and microorganism growth as a result of their decomposition is a significant source of nutrition for many fishes and shrimps.

Detritivores (of which the amount of species in the trade is legion), have always done very well in botanical-method aquariums, and the accumulation of biofilms and microbial growth is something that we've discussed for a long time. By their very nature, the structure and decomposition of botanical materials make the "functional aesthetics" of our aquariums an important way to accommodate the natural feeding behaviors of our fishes.

So, the answer to the question (literally!), "Who has the (literal) guts for this stuff?" is quite possibly, "everyone!" 

Now, while while we're on the subject of loricariids, a further scan of scientific literature revealed some interesting things about what these fishes are actually taking in when they "graze" in the wild. It's kind of eye opening, to me. One study revealed that loricariids consumed five principal items: sponges, organic detritus, bryophytes, bryozoans and sediment.

Wood is definitely part of the equation somewhere, but for the species examined in one of the studies I found (Rhinelepis aspera, Hypostomus regani, H. ternetzi, H. maragaritifer, H. microstomus, and Megalancistrus aculeatus) the gut content analysis was quite revealing:

The food spectrum of R. aspera is primarily "organic detritus and small quantities of sediment"; with few periphytic organisms. Although H. regani was found to consume large quantities of organic detritus as well, it also consumed "plant detritus, various sediment, and periphytic organisms" (i.e.; bryozoans, sponges and aquatic insect larvae). Bryozoans and sponges, huh?

Wow! Freshwater sponges...

The study indicated that bryozoans and organic detritus were the main food food of H. ternetzi, which, according to the gut contents of a number of individuals,  tended to consume more sediment, rotifers, chironomids (i.e.; "Bloodworms'), gastropods and harpacticoids than the other species. mean, like "copepods?" Stuff we as reefers feed all the time? H. margaritifer was found to ingest plant material. Other periphytic organisms such as insect larvae, and those bryozoans and sponges contributed to the diet of H. margaritifer.

And it gets more interesting still...

Sponges- I can't let that go.

Sponges were the principal food resource of H. microstomus and M. aculeatus, along with a healthy does of chironomids, various gastropods, Trichoptera (insects), and some bryozoans also consumed. Diets of these two fishes were composed of larger-sized items, with the finer organic detritus and such being less important than it was to the other species in the study. 

This kind of information is tantalizing. It's compelling. 

And what really gets me going is learning that some of our favorite, most beloved fishes are consuming large quantities of materials that I doubt any freshwater aquarist adds to his/her arsenal of foodstuffs. We're really good at feeding our catfishes baby vegetables and stuff, while typically overlooking many species' surprisingly high dietary dependency on items like insects, bryozoans, harpactoid copepods, and interestingly...sponges!

While we kind of always knew that these fishes ingested wood and "stuff", it's interesting to see what they're actually eating in the wild...especially the "stuff"- and configuring our aquariums and the supplemental and primary feeding opportunities available to the fishes accordingly.

We have some interesting, yet perhaps overlooked possibilities to provide some of these items. 

In fact, there are a number of marine aquarium-purposed foods (typically targeted at certain marine angelfishes, many of which consume significant quantities of sponge) which contain sponges in their formulation. One of my favorite is Ocean Nutrition's "Angel Formula." Granted, these foods contain stuff like mussels, and other marine foods, and the sponges included are marine sponges, but I can't help but wonder if these are that morphologically or nutritionally different/palatable to the fishes than a freshwater/tree sponge would be?

Could the next great frozen Loricarid food include sponges? And we DO have harpactoid copepods available live, and in a variety of other formats intended for marine fishes and corals...Interestingly, I remember that the big "knock" by us reefers, for a long time, about some of these copepods was that they were "freshwater" varieties, and therefore didn't have the "correct" nutritional profile for marine organisms.

Hmm. We're talking about freshwater fishes here, right? Yeah. 

So, like, why the hell haven't we been feeding these foods to our freshwater fishes all of these years?

Try some of these foods with your loricariids..and other fishes as well. What's to lose?

Oh, I can hear the objections: 


Is it?. Online ordering is really cool. It might just catch on.

"Too much work!" 

Really? C'mon. Ever cultured Grindal Worms or wingless fruit flies?  THAT is "too much work" by definition.

"This is ridiculous; No need to experiment with these wacky foods. We're doing just fine now with Zucchini and stuff! Stupid."  

Urghhhhh. "If man was meant to fly, he'd have wings..."

To not experiment is stupid, IMHO. 

Don't be stupid. And I mean that in the kindest way possible. Don't just accept "what works" as "the way." 

Push forward. Experiment. Fail quickly, or move forward rapidly with success. Play a hunch or two. Try something different. This is how advances in the hobby are made. This is how breakthroughs happen.

You gotta try.

Stay studious. Stay curious. Stay observant. Stay engaged. Stay resourceful...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

The commendable power of restraint.

One of the things that we find ourselves doing in the aquarium hobby is using " a little of this and that" in our tanks, because-well- because we seem to be fixated on lots of variety of "stuff" in our tanks, right?

I mean, there is nothing wrong with using a diversity of materials in our aquariums to express our creativity, and I DO own a company which sells a significant variety of natural aquascaping materials...However, I think it's important to consider exactly what it is we're trying to accomplish in our tanks when we select and employ botanical materials in our aquariums.


As we've discussed a lot around here, the idea of using natural materials, like wood, leaves, seed pods, and roots is a faithful representation of many of the wild habitats we obsess over. And more important, it's a functional methodology of fostering natural processes and a healthy ecology in our tanks.

Are you simply trying to add some aquascaping interest to your tank? Are you interested in manipulating the aquarium water chemistry? Perhaps you're attempting to replicate a very specific ecological niche? Setting up a system for breeding fishes or rearing their fry?

There are many, many applications for botanicals in aquariums. A wide range of things you can do with them, and an even wider range of botanicals to do the job. And the most important "job" for botanicals in our aquariums, IMHO, is to foster the ecology of the aquarium...The so-called "microbiome."

And the important thing to know in this context is that you don't have to use 25 different botanicals and leaves in your aquarium to achieve this ecology within your tank. The reality is that, organisms like fungal growth, bacteria, Paramecium, and other microfauna are typically not tied to a specific leaf or seed pod, so not having a huge variety doesn't mean that you won't be able to achieve a significant microbiome within your tank.

So from a "biodiversity" or ecological standpoint, there is no reason why you would need a huge variety of botanicals in a given aquarium. It really boils down to aesthetics. Or, if you're trying to be more "biotopically accurate"- it depends upon the variety of materials that you'd expect to find in the habitat you're interested in replicating.

For example, a flooded forest might have a lot more ( in both density and variety) leaves and seed pods than say, a fast-flowing river, stream, or a small oxbow lake might have. Other locales might simply have a lot of a few materials, like branches and leaves, but minimal amounts of seed pods and other materials. 

Maybe you're not trying to replicate any specific habitat at all. Perhaps it's simply a creative expression with botanicals. That's fine. You can use as many or as little as you want...and you still get the "functional" aspects if you don't "edit" them!

How your botanical-style aquarium looks and (to a lesser extent, functions) is dependent upon these types of characteristics. Yet, it's really a matter of what works best for the aquarium that you are trying to create. The power of restraint is a very important factor when playing with botanicals!

Now again, with all of the cool botanical materials available to hobbyists here and elsewhere, it's certainly fun to use a large variety of different materials in your tank! I personally have always been of the opinion that too much variety in a given tank is sort of distracting and just somehow doesn't always look good. I mean, it certainly just doesn't always! Somehow, using a little less variety in a given tank seems to just look a bit better, IMHO.

However, as we've mentioned already, if you're replicating a specific habitat that might have a wide variety of materials in a given small locale, it makes sense, right?

And there is the benefit of a field of botanicals not only cultivating microbial and fungal food sources for fishes, there is the direct consumption of the botanicals (or their constituent materials) by fishes.

Yes, direct consumption of botanicals by fishes is something that we haven't talked all that much about over the years here.

It's long been known that many species of fishes, particularly Panaque/Panaqolus and some Hypostomus/Cochliodon love botanical stuff. These species are equipped with teeth specifically "designed" to gouge wood. And there's probably another odd one or two that consume it as well. Now, you should be aware that wood "eaters" don't consume the wood per se, they consume it as a "by-product" of their overall feeding strategy.

(The "business end" of Panaque nigrolineatus by Neale Monks, used under CC BY-SA 3.0)

In fact, some recent scientific studies have corroborated digestive enzyme activity profiles and gastrointestinal fermentation levels in the fishes’ GI tracts, suggesting that the "wood-eating catfishes" are not true xylivores, such as beavers and termites, but rather, are detritivores like so many other fishes from the family Loricariidae.

In fact, the conclusion of one study indicated that "..the fishes’ whole digestive strategy ranging from intake, to passage rate, digestive enzyme activities, gastrointestinal fermentation, and decreasing surface area in the distal intestine suggests that these fishes are geared for the digestion and assimilation of soluble components of their detrital diet.

However, the wood-eating catfishes do take macroscopic detritus (i.e., woody debris) and reduce it to <1 mm in diameter, which likely has significant consequences for carbon cycling in their environment. Given that much of the Amazonian basin is unstudied, and much of it is under threat of deforestation (leading to more wood in waterways), the wood-eating catfishes may play a crucial role in the dynamics of the Amazonian ecosystem, and certainly in the reduction of coarse woody debris."

(German DP. Inside the guts of wood-eating catfishes: can they digest wood? Journal of Comparative Physiology B, Biochemical, Systemic, and Environmental Physiology. 2009;179(8):1011-1023. doi:10.1007/s00360-009-0381-1.)

Interesting, right?

And it has some implication for how we keep these fishes in our botanical-style aquariums, right? I mean, we have no shortage of pics of your Plecos tearing into various botanicals, ranging from leaves to seed pods, like the Calotropis pods, Cariniana pods, etc. So, based on the study above, it would suggest that at least part of the pods do form a part of the diet of these fishes, and in the process of consuming them, the fishes are helping enrich the aquarium habitat. 

Now, the botanicals themselves may not be "the whole meal" for many fishes, but the biofilms, algal threads, and other biocover which grow on them do provide foraging for many fishes. A number of us have noticed a wide-ranging variety of fishes, from Barbs to characin to cichlids, feeding actively on the materials on the materials which are "recruited" by submerged botanicals.

This type of activity has led me to postulate that the use of botanicals can perform a definite "feeding support function" for a wide variety of fishes. So, I suppose, one advantage of a variety of botanical materials in one tank is that it increases your chances of having something palatable to someone in the tank!

If you've followed us for any length of time, you're well aware that we are not just pushing you to play with natural, botanical-style aquariums only for the pretty aesthetics. I mean, yeah, they look awesome, but there is so much more to it than that. We are almost as obsessed with the function of these aquariums and the wild habitats which they attempt to represent!



Understanding why you're choosing to throw botanicals in your aquarium is as important as it is to understand how to employ them. Regardless of how you employ the botanicals, I cannot stress enough the need to go SLOWLY. There is no need to rush and dump everything in at one time, or in huge quantities. Particularly in an established aquarium, where your animals are used to a certain stable range of parameters...It goes without saying that if your introducing materials which can influence water chemistry and quality, you will need to go slow and exercise common sense.

And, since botanicals are actively "breaking down" in your aquarium over their "service lifetimes", it's important to employ good husbandry techniques (i.e.; monitoring of water quality, water changes, regular filter media changes, etc.). Just remind yourself that aquatic botanicals create a "dynamic" environment, and you'll enjoy using them that much more!

Apart from, "What pods should I use for a _____________ style setup?" the most common question we receive is ""Do I leave them in or let them break down in my tank?"

And of course, our simple, likely unsatisfying answer is..."It's your call!"

It's as much about your aesthetic preferences as it is long-term ecological stability of the aquarium. It's a decision that each of us makes based on our tastes, management "style", and how much of a "mental shift" we've made o except the transient nature of a botanical-style aquarium and its function. There really is no "right" or "wrong" answer here. It's all about how much you enjoy what happens  naturally versus what you choose to control in your tank.

I tend to favor Nature. Every time. It's not even close. 

But that's just me.

And of course, we can't ever lose sight of the fact that we're creating and adding to a closed aquatic ecosystem, and that our actions in how we manage our tanks must map to our ambitions, tastes, and the "regulations" that Nature imposes upon us.

Yes, anything that you add into your aquarium that begins to break down is bioload.

Everything that imparts proteins, lignins, tannins, organics, etc. into the water is something that you need to consider. However, it's always been my personal experience and opinion that, in an otherwise well-maintained aquarium, with regular attention to husbandry, stocking, and maintenance, the"burden" of botanicals on your water quality is surprisingly insignificant.

Even in test systems which I intentionally "neglected" by conducting very sporadic water exchanges, once I hit my preferred "population" of botanicals (by building them up gradually), I have never noticed significant phosphate or nitrate increases that could be attributed to their presence.


So, once and for all- is adding a bunch of botanicals to your aquarium "dangerous?"

I mean, it could be, in some instances. Like, adding large quantities of fresh botanicals to an established, stable tank all at once is a recipe for problems. But, this is "Aquarium Keeping 101", right? Like, what would you expect that would happen? Why would you even do that?

It's about common sense.

The reality is, adding botanicals to your tank and using them, replacing them regularly, etc, is no more "dangerous" than anything else we do as aquarists. You simply need to go slowly, apply common sense, follow our prep instructions, and observe your tank carefully.

Look, stuff can still occasionally go wrong, even when you follow instructions and employ common sense. Never lose sight of the fact that aquariums are closed natural ecosystems, and changing the delicate ecological balance within them always risks disrupting established biological processes- and that can have consequences for your fishes.

But, you already KNOW that

It's the reality of Nature, and a reminder that, although we can control some things, Mother Nature calls the shots...

So, the power of "chilling out"- the ability to exercise restraint; to not go crazy adding a ton of stuff all at once- is a huge and very, very important skill for all who play with botanicals to acquire. 

I'll bet that you already have.

Stay creative. Stay curious. Stay excited. Stay restrained...

And Stay Wet.


Scott Fellman

Tannin Aquatics 





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

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


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

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

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

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

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

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

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

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

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

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

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

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

Again, just like Nature.

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

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

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

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

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

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

It  just makes sense, right?


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

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

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

There are numerous life forms which are found on ad among these materials as well, such as fungal growths, bacterial biofilms, etc. which we likely never really consider, yet are found in abundance in nature and in the aquarium, and perform vital roles in the function of the aquatic habitat.

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

(Spongilla lacustris Image by Kirt Onthank. Used under CC-BY SA 3.0)

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

Oh, cool!

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

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

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

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

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

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

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

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

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

And Stay Wet.


Scott Fellman

Tannin Aquatics 




The slow(er) road to success with fish stocking...

One of the questions which we are asked less and less these days is, 'What kinds of fishes are suitable for a botanical-style aquarium?" I think that after 6 years of pounding all of these ideas into your heads about all of the strange nuances of botanical-style aquariums, it's almost universally understood that pretty much any fishes can live in them.

On the other hand, when it comes to how we stock our tanks, nothing has really changed...however, it could. And it should, IMHO.

We spend a pretty good amount of time studying, scheming, and pondering how to create a compatible, interesting, and attractive community of fishes within our aquariums.

It's probably among the most enjoyable things that we do in the hobby, right?

As a somewhat eccentric philosopher of all things fish, one of my favorite things to ponder is stuff that we do while creating our aquariums which is- intentionally or otherwise- analogous to the factors in Nature that result in the environments and fish populations that we find so compelling.

If you're like me, you likely spend a little too much time pondering all sorts of arcane aspects of the hobby...Okay, so maybe you're NOT like me, but you probably have a rather keen interest in the way Nature operates in the wild aquatic systems of the world, and stock your aquariums accordingly.

As one who studies a lot of details about some of the habitats from which our fishes come, I can't help but occasionally wonder exactly what it is that brings fishes to a given location or niche within a environment?

Now, the first answer we're likely to proffer is the most apparent...right? I mean, they follow the food!

Fishes tend to move into new areas in search suitable food sources as part of their life cycle. And food sources often become available in habitats such as flooded forest areas after the rains come, when decomposing leaves and botanical materials begin to create (or re-activate, as the case may be) "food webs", attracting ever more complex life forms into the area.

When we create our aquariums, we take into consideration a lot of factors, ranging from the temperament and size of our fish selections, to their appearance, right? These are all important factors. However, have you ever considered what the factors are in nature which affect the composition of a fish community in a given habitat?

Like, why "x" fish is living in a particular habitat?

What adaptations has the fish made that make it uniquely suitable for this environmental niche? Further, have you thought about how we as hobbyists replicate, to some extent, the actual selection processes which occur in Nature in our quest to create the perfect community aquarium?

Now, if you're an African Cichlid lover or reef hobbyist, I'm sure you have!

Social hierarchies, spatial orientations, and allopathic processes are vital to success in those types of aquariums; you typically can't get away with just throwing in a random fish or coral and hoping it will just mix perfectly.

However, for many hobbyists who aim to construct simple "community tanks", it isn't that vital to fill specific niches and such...we probably move other factors to the forefront when thinking about possible additions to our community of fishes: Like, how cool the fish looks, how large it grows, if it has a peaceful temperament, etc. More basic stuff.

However, in the end, we almost always make selections based upon factors which we deem important...again, a sort of near-mimicry of natural processes- and how the fishes work in the habitat we've created for them.

"Unnatural selection?" Or...Is it essentially what nature's does for eons?

Oh, and what exactly is an "aquatic habitat", by the way? In short, you could say that an aquatic habitat is the physical, chemical, and biological characteristics which determine the suitability for habitation and reproduction of fishes.

Of course, these characteristics can determine which fishes are found in a given area in the wild- pretty much without exception. It's been happening for eons.

Approaching the stocking of an aquarium by determining which fishes would be appropriate for the physical characteristics of the tank is not exactly groundbreaking stuff.

However, when we evaluate this in the context of "theme", and what fish would be found within, say, an Amazonian Igarape stream or a Southeast Asian peat swamp, the idea of adding fishes to "exploit" the features of the habitat we've created is remarkably similar to the processes which occur in Nature that determine what fish are found there, and it's the ultimate expression of good tank planning, IMHO.

It's just kind of interesting to think about in that context, right?

Competition is another one of the important factors in determining  how fish populations in the wild. Specifically, competition for space, resources (e.g.; food) and mates are prevalent. In our aquariums, we do see this to some extent, right? The "alpha male" cichlid, the Pleco that gets the best cave, and the Tetra which dominates his shoal.

How we create the physical space for our fishes can have significant impact on this behavior. When good hiding spaces are at a premium, as are available spawning partners, their will be some form of social hierarchy, right?

Other environmental factors, such as  water movement, dissolved oxygen, etc. are perhaps less impactful on our community once the tank is established. However, these factors figure prominently in our decisions about the composition of, or numbers or fishes in the community, don't they?

For example, you're unlikely to keep Hillstream loaches in a near stagnant, blackwater swamp biotope aquarium, just like you'd be unlikely to keep Altum Angelfish in a fast-moving stream biotope representation. And fishes which shoal or school will, obviously, best be kept in numbers.

"Aquarium Keeping 101", again.

One factor that we typically don't have in our aquaria is predation. I know very few aquarists who would be sadistic enough to even contemplate trying to keep predators and prey in the same tank, to let them "have at it" and see what happens, and who comes out on top!

I mean, there is a lot to this stuff, isn't there?

Again, the idea of creating a tank to serve the needs of certain fishes isn't earth-shattering. Yet, the idea of stocking the tank based on the available niches and physical characteristics is kind of a cool, educational, and ultimately very gratifying process. I just think it's truly amazing that we're able to actually do this these days.

And the sequence that you stock your tank in is extremely pertinent.

I think that you could literally create a sort of "sequence" to stocking various types of fishes based on the stage of "evolution" that your aquarium is in, although the sequence might be a bit different than Nature in some cases. For example, in a more-or-less brand new aquarium, analogous in this case to a newly-inundated forest floor, their might be a lot less in the way of lower life forms, such as fungi and bacteria, until the materials begin breaking down. You'd simply have an aggregation of fresh leaves, twigs, seed pods, soils, etc. in the habitat.

So, if anything, you're likely to see fishes which are much more dependent upon  allochthonous from the terrestrial environment. This is a compelling way to stock an aquarium, I think. Especially aquarium systems like ours which make use of these materials en masse.

Right from the start (after cycling, of course!), it would not be unrealistic to add fishes which feed on terrestrial fruits and botanical materials, such as Colossoma, Arowanna, Metynis, etc. Fishes which, for most aquarists of course, are utterly impractical to keep because of their large adult size and/or need for physical space!

(Pacu! Image by Rufus46, used under CC BY-SA 3.0)

Now, a lot of smaller, more "aquarium suited" fishes will also pick at these fruits and seeds, so you're not totally stuck with the big brutes if you want to go this route! Interestingly, the consumption and elimination of fruits by fishes is thought to be a major factor in the distribution of many plants in the region.

Do a little research here and you might be quite surprised about who consumes what in these habitats!

More realistically for most aquarists, I'd think that you could easily stock first with fishes like surface-dwelling (or near surface-dwelling) species, like hatchetfishes and some Pencilfishes, which are largely dependent upon terrestrial insects such as flies and ants, in Nature. In other words, they tend to "forage" or "graze" little, and are more opportunistic, taking advantage of careless insects which end up in the water of these newly-inundated environs.

I've read studies where almost 100 species were documented which feed near-exclusively on insects and arthropods from terrestrial sources in these habitats! As I mention often, if you dive a bit deeper than the typical hobbyist writings, and venture into scholarly materials and species descriptions, you'll be fascinated to read about the gut-content analysis of fishes, because they give you a tremendous insight about what to feed in the aquarium!

Continuing on, it's easy to see that, as the environments evolve, so does the fish population. And the possibilities for simulating this in the aquarium are many and are quite interesting!

Later, as materials start to decompose and are acted on by fungi and bacteria, you could conceivably add more of the "grazing" type fishes, such as Plecos, small Corydoras, Headstanders, etc.

As the tank ages and breaks in more, this would be analogous to the period of time when micro-crustaceans and aquatic insects are present in greater numbers, and you'd be inclined to see more of the "micropredators" like characins, and ultimately, small cichlids.

Interestingly, scientists have postulated that evolution favored small fishes like characins in these environments, because they are more efficient at capturing small terrestrial insects and spiders in these flooded forests than the larger fishes are!

And it makes a lot of sense, if you look at it strictly from a "density/variety" standpoint- lots of characins call these habitats home!

Then there are detritivores.

The detrivorus fishes remove large quantities of this material from submerged trees, branches, etc. Now, you might be surprised to learn that, in the wild, the gut-content analysis of almost every fish indicates that they consume organic detritus to some extent! And it makes sense...They work with the food sources that are available to them!

At different times of the year, different food sources are easier to obtain.

And, of course, all of the fishes which live in these habitats contribute to the surrounding forests by "recycling" nutrients locked up in the detritus. This is thought by ecologists to be especially important in blackwater inundated forests and meadows in areas like The Pantanal, because of the long periods of inundation and the nutrient-poor soils as a result of the slow decomposition rates.

All of this is actually very easy to replicate, to a certain extent, when stocking our aquaria. Why would you stock in this sort of sequence, when you're likely not relying on decomposing botanicals and leaves and the fungal and microbial life associated with them as your primary food source?

Well, you likely wouldn't be...However, what about the way that the fishes, when introduced at the appropriate "phase" in the tank's life cycle- adapt to the tank? Wouldn't the fishes take advantage of these materials as a supplement to the prepared foods that you're feeding them? Doesn't this impact the fishes' genetic "programming" in some fashion? Can it activate some health benefits, behaviors, etc?

I believe that it can. And I believe that this type of more natural feeding ca profoundly and positively impact our fishes' health.

I’m no genius, trust me. I don’t have half the skills many of you do but I have succeeded with many delicate “hard-to-feed” fishes over my hobby “career.” 


Because I'm really patient.

Success with this approach is simply a result of deploying "radical patience."  The practice of just moving really slowly and carefully when adding fishes to new tanks. 

It's a really simple concept.

The hard part is waiting longer to add fishes.

Wait a minimum of three weeks—and even up to a month or two if you can stand it, and you will have a surprisingly large population of micro and macro fauna upon which your fishes can forage between feedings.

Having a “pre-stocked” system helps reduce a considerable amount of stress for new inhabitants, particularly for wild fishes, or fishes that have reputations as “delicate” feeders.

And think about it. This is really a natural analog of sorts. Fishes that live in inundated forest floors (yeah, the igapo again!) return to these areas to "follow the food" once they flood.

It just takes a few weeks, really. You’ll see fungal growth. You'll see some breakdown of the botanicals brought on by bacterial action or the feeding habits of small crustaceans and fungi. If you "pre-stock", you might even see the emergence of a significant  population of copepods, amphipods, and other creatures crawling about, free from fishy predators, foraging on algae and detritus, and happily reproducing in your tank.

We kind of know this already, though- right?

This is really analogous to the tried-and-true practice of cultivating some turf algae on rocks either in or from outside your tank before adding herbivorous, grazing fishes, to give them some "grazing material." 

Radical patience yields impressive results.

It’s not always easy to try something a little out of the ordinary, or a bit against the grain of popular practice, but I commend you for even thinking about the idea. At the very least, it may give you pause to how you stock your tank in the future, like  "Herbivores first, micro predators last", or whatever thought you subscribe to. 

Allow your system to mature and develop at least some populations of fauna for these fishes to supplement their diets with. You’ll develop a whole new appreciation for how an aquarium evolves when you take this long, but very cool road.

Stay patient. Stay observant. Stay creative. Stay studious. Stay resourceful...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


The Botanical-Style Aquarium: A "filter" of its own, and other biological musings...

A big thought about our botanical-style aquariums:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Let's summarize:

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

2) Allow biofilms and fungal growths to proliferate.

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

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

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

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

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

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

I'd be remiss if I didn't at least touch on the idea of feeding your aquarium. Think about it: When you feed your fishes, you are effectively feeding all of the other life forms which comprise this microbiome. You're "feeding the aquarium." When fishes consume and eliminate the food, they're releasing not only dissolved organic wastes, but fecal materials, which are likely not fully digested. The nutritional value of partially digested food cannot be understated. Many of the organisms which live within the botanical bed and the resulting detritus will assimilate them.

Now, we could go on and on about this topic; there is SO much to discuss. However, let's just agree that feeding our fishes is another critical activity which provides not only for our fishes' well-being, but for the other life forms which create the ecology of the aquarium.

And, let's be clear about another thing: Detritus, the nemesis of many aquarists- is NOT our enemy. We've talked about this for several years now, and I cannot stress it enough: To remove every bit of detritus in our tanks is to deprive someone, somewhere along the food chain in our tanks, their nutritional source. And when you do that, imbalances occur...You know, the kinds which cause "nuisance algae" and those "anomalous tank crashes."

The definition of this stuff, as accepted in the aquarium hobby, is kind of sketchy in this regard; not flattering at the very least:

"detritus is dead particulate organic matter. It typically includes the bodies or fragments of dead organisms, as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose or remineralize the material."

Shit, that's just bad branding.

The reality is that this not a "bad" thing. Detritus, like biofilms and fungi, is flat-out misunderstood in the hobby.

Could there be some "upside" to this stuff? 

Of course there is. 

I mean, even in the above the definition, there is the part about being "colonized by communities of microorganisms which act to decompose or remineralize..."

It's being processed. Utilized. What do these microorganisms do? They eat it...They render it inert. And in the process, they contribute to the biological diversity and arguably even the stability of the system. Some of them are utilized as food by other creatures. Important in a closed system, I should think.

This is really important. It's part of the biological operating system of our botanical-style aquariums. I cannot stress this enough. 

Now, I realize that the idea of embracing this stuff- and allowing it to accumulate, or even be present in your system- goes against virtually everything we've been indoctrinated to believe in about aquarium husbandry. Pretty much every article you see on this stuff is about its "dangers", and how to get it out of your tank. I'll say it again- I think we've been looking at detritus the wrong way for a very long time in the aquarium hobby, perceiving it as an "enemy" to be feared, as opposed to the "biological catalyst" it really is!

In essence, it's organically rich particulate material that provides sustenance, and indeed, life to many organisms which, in turn, directly benefit our aquariums.

We've pushed this narrative many times here, and I still think we need to encourage hobbyists to embrace it more.

Yeah, detritus.

Okay, I'll admit that detritus, as we see it, may not be the most attractive thing to look at in our tanks. I'll give you that. It literally looks like a pile of shit! However, what we're talking about allowing to accumulate isn't just fish poop and uneaten food. It's broken-down materials- the end product of biological processing.  And, yeah, a wide variety of organisms have become adapted to eat or utilize detritus.

There is, of course, a distinction.

One is the result of poor husbandry, and of course, is not something we'd want to accumulate in our aquariums. The other is a more nuanced definition. 

As we talk about so much around here- just because something looks a certain way doesn't mean that it alwaysa bad thing, right?

What does it mean? Take into consideration why we add botanicals to our tanks in the first place. Now, you don't have to have huge piles of the stuff littering your sandy substrate. However, you could have some accumulating here and there among the botanicals and leaves, where it may not offend your aesthetic senses, and still contribute to the overall aquatic ecosystem you've created.

If you're one of those hobbyists who allows your leaves and other botanicals to break down completely into the tank, what really happens? Do you see a decline in water quality in a well-maintained system? A noticeable uptick in nitrate or other signs? Does anyone ever do water tests to confirm the "detritus is dangerous" theory, or do we simply rely on what "they" say in the books and hobby forums?

Is there ever a situation, a place, or a circumstance where leaving the detritus "in play" is actually a benefit, as opposed to a problem?

I think so. Like, almost always.

Yes, I know, we're talking about a closed ecosystem here, which doesn't have all of the millions of minute inputs and exports and nuances that Nature does, but structurally and functionally, we have some of them at the highest levels (ie; water going in and coming out, food sources being added, stuff being exported, etc.).

There is so much more to this stuff than to simply buy in unflinchingly to overly-generalized statements like, "detritus is bad."

The following statement may hurt a few sensitive people. Consider it some "tough love" today: 

If you're not a complete incompetent at basic aquarium husbandry, you won't have any issues with detritus being present in your aquarium.


Don't overstock.

Don't overfeed.

Don't neglect regular water exchanges.

Don't fail to maintain your equipment.

Don't ignore what's happening in your tank.

This is truly not "rocket science." It's "Aquarium Keeping 101."

And it all comes full circle when we talk about "filtration" in our aquariums.

People often ask me, "What filter do you use use in a botanical-style aquarium?" My answer is usually that it just doesn't matter.  You can use any type of filter. The reality is that, if allowed to evolve and grow unfettered, the aquarium itself- all of it- becomes the "filter." 

You can embrace this philosophy regardless of the type of filter that you employ.

My sumps and integrated filter compartments in my A.I.O. tanks are essentially empty.

I may occasionally employ some activated carbon in small amounts, or throw some "Shade" sachets in there if I am feeling it- but that's it. The way I see it- these areas, in a botanical-style aquarium, simply provide more water volume, more gas exchange; a place for bacterial attachment (surface area), and perhaps an area for botanical debris to settle out. Maybe I'll remove them, if only to prevent them from slowing down the flow rate of my return pumps.

But that's it. 

A lot of people are initially surprised by this. However, when you look at it in the broader context of botanical style aquariums as miniature ecosystems, it all really makes sense, doesn't it? The work of these microorganisms and other life forms takes place throughout the aquarium.

I admit, there was a time when I was really fanatical about making sure every single bit of detritus and fish poop and all that stuff was out of my tanks. About undetectable nitrate. I was especially like that in my earlier days of reef keeping, when it was thought that cleanliness was the shit!

It wasn't until years into my reef keeping work, and especially in my coral propagation work, that I begin to understand the value of food, and the role the it plays in aquatic ecosystems as a whole. And that "food" means different things to different aquatic organisms. The idea of scrubbing and removing every single trace of what we saw as "bad stuff" from our grow-out raceways essentially deprived the corals and supporting organisms of an important natural food source.

We'd fanatically skim and remove everything, only to find out that...our corals didn't look all that good. We'd compensate by feeding more heavily, only to continue to remove any traces of dissolved organics from the water...

It was a constant struggle- the metaphorical "hamster wheel"- between keeping things "clinically clean" and feeding our animals. We were super proud of our spotless water. We had a big screen when you came into our facility showing the parameters in each raceway. Which begged the question: Were we interested in creating sterile water, or growing corals? 

Eventually, it got through my thick skull that aquariums- just like the wild habitats they represent-are not spotless environments, and that they depend on multiple inputs of food, to feed the biome at all levels. This meant that scrubbing the living shit (literally) out of our aquariums was denying the very biotia which comprised our aquariums their most basic needs.

That little "unlock" changed everything for me.

Suddenly, it all made sense. 

This has carried over into the botanical-style aquarium concept: It's a system that literally relies on the biological material present in the system to facilitate food production, nutrient assimilation, and reproduction of life forms at various trophic levels.

It's changed everything about how I look at aquarium management and the creation of functional closed aquatic ecosystems. 

It's really put the word "natural" back into the aquarium keeping parlance for me. The idea of creating a multi-tiered ecosystem, which provides a lot of the requirements needed to operate successfully with just a few basic maintenance practices, the passage of time, a lot of patience, and careful observation.

It means adopting a different outlook, accepting a different, yet very beautiful aesthetic. It's about listening to Nature instead of the asshole on Instagram with the flashy, gadget-driven tank. It's not always fun at first for some, and it initially seems like you're somehow doing things wrong.

It's about faith. Faith in Mother Nature, who's been doing this stuff for eons.

It's about nuance.

It's about looking at things a bit different that we've been "programmed" to do in the aquarium hobby for so long. It's about not being afraid to question the reasons why we do things a certain way in the hobby, and to seek ways to evolve and change practices for the benefits of our fishes. 

It takes time to grasp this stuff. However, as with so many things that we talk about here, it's not's simply an evolution in thinking about how we conceive, set up, and manage our aquariums. 


Sure, the aquairum is a "filter" of sorts, if you want to label it as such. However, it's so much more: A small, evolving ecosystem, relying on natural processes to bring it to life.

Wrap you head around that.

It might just change everything in the hobby for you.

Stay open-minded. Stay thoughtful. Stay bold. Stay curious. Stay diligent. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics 





What our fishes eat...The wonder of food webs.

Yes, I admit that we talk about some rather obscure topics around here. Yet, many of these topics are actually pretty well known, and even well-understood by science. We just haven't consciously applied them to our aquarium work...yet.

One of the topics that we talk about a lot are food webs. To me, these are fascinating, fundamental constructs which can truly have important influence on our aquariums.

So, what exactly is a food web?


A food web is defined by aquatic ecologists as a series of "trophic connections" (ie; feeding and nutritional resources in a given habitat) among various species in an aquatic community. 

All food chains and webs have at least two or three of these trophic levels. Generally, there are a maximum of four trophic levels. Many consumers feed at more than one trophic level.

So, a trophic level in our case would go something like this: Leaf litter, bacteria/fungal growth, crustaceans...

In the wild aquatic habitats we love so much, food webs are vital to the organisms which live in them. They are an absolute model for ecological interdependencies and processes which encompass the relationship between the terrestrial and aquatic environments.

In many of the blackwater aquatic habitats that we're so obsessed with around here, like the Rio Negro, for example, studies by ecologists have determined that the main sources of autotrophic sources are the igapo, along with aquatic vegetation and various types of algae. (For reference, autotrophs are defined as organisms that produce complex organic compounds using carbon from simple substances, such as CO2, and using energy from light (photosynthesis) or inorganic chemical reactions.)

Hmm. examples would be phytoplankton!

Now, I was under the impression that phytoplankton was rather scarce in blackwater habitats. However, this indicates to scientists is that phytoplankton in blackwater trophic food webs might be more important than originally thought! 

Now, lets get back to algae and macrophytes for a minute. Most of these life forms enter into food webs in the region in the form of...wait for it...detritus! Yup, both fine and course particular organic matter are a main source of these materials. I suppose this explains why heavy accumulations of detritus and algal growth in aquaria go hand in hand, right? Detritus is "fuel" for life forms of many kinds.

In Amazonian blackwater rivers, studies have determined that the aquatic insect abundance is rather low, with most species concentrated in leaf litter and wood debris, which are important habitats.  Yet, here's how a food web looks in some blackwater habitats : Studies of blackwater fish assemblages indicated that many fishes feed primarily on burrowing midge larvae (chironomids, aka "Bloodworms" ) which feed mainly with organic matter derived from terrestrial plants!

And of course, allochtonous inputs (food items from outside of the ecosystem), like fruits, seeds, insects, and plant parts, are important food sources to many fishes.  Many midwater characins consume fruits and seeds of terrestrial plants, as well as terrestrial insects.

Insects in general are really important to fishes in blackwater ecosystems. In fact, it's been concluded that the the first link in the food web during the flooding of forests is terrestrial arthropods, which provide a highly important primary food for many fishes.

These systems are so intimately tied to the surrounding terrestrial environment. Even the permanent rivers have a strong, very predictable "seasonality", which  provides fruits, seeds, and other terrestrial-originated food resources for the fishes which reside in them. It's long been known by ecologists that rivers with predictable annual floods have a higher richness of fish species tied to this elevated rate of food produced by the surrounding forests.



And of course, fungal growths and bacterial biofilms are also extremely valuable as food sources for life forms at many levels, including fishes. The growth of these organisms is powered by...decomposing leaf litter! 

Sounds familiar, huh?

So, how does a leaf break down? It's a multi-stage process which helps liberate its constituent compounds for use in the overall ecosystem. And one that is vital to the construction of a food web.

The first step in the process is known as leaching, in which nutrients and organic compounds, such as sugars, potassium, and amino acids dissolve into the water and move into the soil.The next phase is a form of fragmentation, in which various organisms, from termites (in the terrestrial forests) to aquatic insects and shrimps (in the flooded forests) physically break down the leaves into smaller pieces. 

As the leaves become more fragmented, they provide more and more surfaces for bacteria and fungi to attach and grow upon, and more feeding opportunities for fishes!

Okay, okay, this is all very cool and hopefully, a bit interesting- but what are the implications for our aquariums? How can we apply lessons from wild aquatic habitats vis a vis food production to our tanks? 

This is one of the most interesting aspects of a botanical-style aquarium: We have the opportunity to create an aquatic microcosm which provides not only unique aesthetics- it provides nutrient processing, and to some degree, a self-generating population of creatures with nutritional value for our fishes, on a more-or-less continuous basis.

Incorporating botanical materials in our aquariums for the purpose of creating the foundation for biological activity is the starting point. Leaves, seed pods, twigs and the like are not only "attachment points" for bacterial biofilms and fungal growths to colonize, they are physical location for the sequestration of the resulting detritus, which serves as a food source for many organisms, including our fishes.

Think about it this way: Every botanical, every leaf, every piece of wood, every substrate material that we utilize in our aquariums is a potential component of food production!

The initial setup of your botanical-style aquarium will rather easily accomplish the task of facilitating the growth of said biofilms and fungal growths. There isn't all that much we have to do as aquarists to facilitate this but to simply add these materials to our tanks, and allow the appearance of these organisms to happen. 


You could add pure cultures of organisms such as Paramecium, Daphnia, species of copepods (like Cyclops), etc. to help "jump start" the process, and to add that "next trophic level" to your burgeoning food web. 

In a perfect world, you'd allow the tank to "run in" for a few weeks, or even months if you could handle it, before adding your fishes- to really let these organisms establish themselves. And regardless of how you allow the "biome" of your tank to establish itself, don't go crazy "editing" the process by fanatically removing every trace of detritus or fragmented botanicals.

When you do that, you're removing vital "links" in the food chain, which also provide the basis for the microbiome of our aquariums, along with important nutrient processing.

So, to facilitate these aquarium food webs, we need to avoid going crazy with the siphon hose! Simple as that, really!

Yeah, the idea of embracing the production of natural food sources in our aquariums is elegant, remarkable, and really not all that surprising. They will virtually spontaneously arise in botanical-style aquariums almost as a matter of course, with us not having to do too much to facilitate it.

It's something that we as a hobby haven't really put a lot of energy in to over the years. I mean, we have spectacular prepared foods, and our understanding of our fishes' nutritional needs is better than ever.

Yet, there is something tantalizing to me about the idea of our fishes being able to supplement what we feed. In particular, fry of fishes being able to sustain themselves or supplement their diets with what is produced inside the habitat we've created in our tanks!


A true gift from Nature. 

I think that we as botanical-style aquarium enthusiasts really have to get it into our heads that we are creating more than just an aesthetic display. We need to focus on the fact that we are creating functional microcosms for our fishes, complete with physical, environmental, and nutritional aspects.

Food production- supplementary or otherwise- is something that not only is possible in our tanks; it's inevitable.

I firmly believe that the idea of embracing the construction (or nurturing) of a "food web" within our aquariums goes hand-in-hand with the concept of the botanical-style aquarium. With the abundance of leaves and other botanical materials to "fuel" the fungal and microbial growth readily available, and the attentive husbandry and intellectual curiosity of the typical "tinter", the practical execution of such a concept is not too difficult to create.

We are truly positioned well to explore and further develop the concept of a "food web" in our own systems, and the potential benefits are enticing! 

Work the web- in your own aquarium!

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

And Stay Wet.


Scott Fellman

Tannin Aquatics