Common threads and functional aesthetics...

I like to look back on some of my favorite tanks over the years, and they have some  interesting commonalities. Generally, these include things like certain elements used in the "operating system" of the aquarium.  Things which operate very similarly to the natural habitats which they aspire to recreate in the aquairum.

What do I mean? Read on!

The idea of biotope aquariums is well-covered territory in the hobby. I really don't need to discuss the whole concept with you. However, the idea of 'biotope" or "biotope-inspired" aquariums should be, in my humble opinion, more than just trying to capture the look of a habitat. The finest biotope-inspired systems foster the function as much as the aesthetics.

And, when we approach recreating some of these habitats from a "function forward" approach, as opposed to just trying to recreate the look, not only do you create interesting "operational parameters", you get many unusual benefits as well- some of which are analogous to those which the natural environment offers to the organisms which reside there. And of course, the aesthetics often look substantially different than what you get when you just go "diorama mode."

One of my favorites is an aquarium that I set up earlier in the year to represent the form and function of a flooded Pantanal grassland. This was a very different interpretation of a very unique ecological system.

For those of you who aren't familiar with it, The Pantanal (derived from the Portuguese word "pantano"- meaning "swamp", "wetland", or "marsh") is the largest wetlands region Earth. Full stop. Primarily located within the Brazilian state of Mato Grosso do Sul, it also extends into the state of Mato Grosso, and the nations of Paraguay and Boliva as well! We're talking about region estimated to be as large as 75,00 square miles/195,000 square kilometers!  

It's freakin' huge! 

Essentially a large depression in the earth's crust, the Pantanal constitutes a huge river delta, into which a number of rivers converge, depositing sediments and other biological materials. Now of course, with a habitat this large, there are multiple ecosystems contained in it- as many as 12 have been defined by scientists! 

(Image by Alicia Yo- used under CC BY-SA 3.0)

Now, our main focus is, of course, fishes- and the Pantanal offers plenty of places for fishes to reside in! The cool thing about the Pantanal is that as much as 80% of it is floodplains submerged during the rainy seasons (in which up to 59inches/1,500mm of rainfall have been recorded! That corresponds to water depths which can fluctuate up to 15'/5 meters in some areas!), and is home to an astonishing diversity of fishes and aquatic plants!

With it's enormous expanse of shallow, slowly-flowing water (velocities of no more than 4"/10cm per second are typical), dense vegetation tends to be the norm here- both aquatic and terrestrial.

The water itself tends to be turbid, very slightly tinted, and perhaps even a bit anoxic at times. And, interestingly, the highest levels of pH and dissolved oxygen in these habitats tend to occur when the water level decreases and aquatic and terrestrial plant growth is stimulated. Curiously, however, scientists are not 100% certain if this is because of the plants going crazy with photosynthesis, or mixing of the water column due to influx of water. 

Is there a takeaway here for hobbyists?

Over 400 fish species call this region home. Interestingly, the biological  "keystone species" of The Pantanal is a snail- the "Apple Snail" (Ampullaridae), which is a real survivor, as it has both gills and lungs, which makes survival possible during the early part of the flood season when huge amounts of terrestrial plants decay and use up the available oxygen, resulting in suffocation to all of the larger decomposers in the ecosystem.

This remarkable- and fortunate- adaptation enables the humble snail to consume the majority of the dead plant matter and turn it into "fertilizer" for the aquatic plants...And, in an ultimate sort of insult, really- the snails eventually become feed for other animals.

A rather undignified end for such important creatures, wouldn't you say? 

(The "keystone species"- image by Stijn Ghesquiere, used under CC BY-SA 3.0)

Many of the fishes which are found in The Pantanal are migratory, moving seasonally between the river channels and the flood plain regions. As you might imagine, the bulk of them are detritovorous, feeding on the fine particles from the accumulated sediments and macrophytes (remember them?) within the ecosystem.

Macrophytes supply shelter, food resources and cover for the resident fishes. Still other fishes consume the aquatic insects and microorganisms/biofilms that are recruited in this habitat. Most are well-adapted to the relatively oxygen-poor waters of this vast flood plain.

Characins are represented big-time in this habitat, with species of Moenkhausia, Hyphessobrycon, Pyrhulina, Aphyocharax, and Characidium all present. Oh, and Apisto lovers will be pleased to know that there are some cool ones found there- Apistogramma borellii, A. trifasciata, A. commbrae, and some others. Even species as wide-ranging and diverse as Corydoras, CrenicichlaOtocinculus, Abramites, and Leporinus are found in this ecosystem.

According to most of the studies I read on this ecosystem, the contributing factors to the fish population include stuff like the clarity of the water, the abundance of the food sources (ie, those macrophytes again!), and the connections between lakes and rivers. And, as the water recedes, the available macrophytes tend to settle on the margins of the habitat in the form of...wait for it...our old friend, detritus! 

There's just too much good stuff here, huh?

And during the low-water seasons, the resident fishes tend to occupy the areas where autochthonous resources- materials which formed in the areas where they are found, not from outside of the habitat a la our old friends, the allochthonous resources. 

(Damn, we talk about some obscure shit in this blog, huh?)

Of course, the seasonal flooding of the marginal lowlands increases the quantity and availability of allochthonous feeding resources for the floodplains and the fishes which reside there. An interesting example of the tight relationship between various habitats in the region, wouldn't you say?

When the water levels rise, the marginal vegetation in the habitats dies off and contributes to the levels of organic matter found in the water. This results in a decrease in dissolved oxygen, pH, and transparency of the water column. Those of you who are geeky hardcore biotope hobbyists, who obsess over stuff like creating a tank to represent a habitat in a specific time of year should take note, huh?

Even the lifestyles of the fishes play a role in the "operating system" of the environment.

Biologists tend to think that the small guys- the characins, specifically, benefit from fast growth, high fecundity (ie; they're prolific!), and rapid colonization capabilities- and that these characteristics tend to determine success in The Pantanal environment. And one more example of this is the "role" of fishes in the Pantanal which consume fruits (which come from the trees adjacent to the wetlands).  Around 150 species of fruit-eating fishes inhabit this system- that's a remarkable number!

When the fishes eat the fruits, they pass the seeds through, well- pooping. Amazingly, it's thought  that they are responsible for the dispersal of as much as 95% of the trees which comprise tropical forests of the region! That's literally the definition of "doing useful shit", IMHO...

This habitat is just FILLED with possibilities for replication!

This relative absence of representation of this habitat in the natural aquarium hobby tells me that not only is The Pantanal ripe for replication- it's a perfect ground-floor opportunity for studying, discovering, and creating evolutions and breakthroughs in the hobby. To work on replicating some of the function of the habitat as well as the form.

Okay, so we touched on that habitat enough to (I hope) whet your appetite to find out a little more and attempt to replicate its form and function in an aquarium!

And that's kind of what we're gonna do. I hope you join us there, too. At the place where what we know and what we think about in the aquarium hobby meet. At that "delta" at the intersection of science and art.

The aquarium that I created to replicate this flooded environment really went together easily... the "ingredients" are readily available...

It starts with a sedimented bottom layer, replete with dried leaves and some terrestrial grasses, maybe some twigs or submerged pieces of dried weeds. That not only helps recreate some of the look, it helps to foster the function as well.

That's the easy part of this whole thing. 

It's hardly "revolutionary" or even crazy...Yet, to attempt to replicate one of these complex natural habitats in the aquarium requires us to look ourselves in the mirror and see if we're up to the challenges (aesthetic and otherwise).

It looks weird. It involves ideas that we've touched on here for years- decomposition, fungi, turbidity, and...mental shifts.

Had enough of this shit? Or, are you thirsty for more?

I submit to you the idea of turbid, sediment-filled tanks, where dead branchy materials, decomposing leaves, twigs, biofilms, clays, soil and silt play...

This type of feature really pushes us out of our comfort zone.

You have silty, sedimented material which, when disturbed, will cloud the water a bit for days at a time. Sort of like what happens in Nature- but it's in your living room.

Could you handle this?

What's the "upside" to a tank like this?

Well, for one thing, you have the benefit of a substrate which actively leaches minerals, organic materials, and other compounds into the aquarium.  It also fosters  the growth and proliferation of fungi, bacteria, and microorganisms, which not only facilitate processing of dissolved organics, but serve as a supplemental food sources for our fishes.

In my 'late season Panatanal" tank, the water quality was great. I had nitrate levels which were almost undetectable, despite the presence of large quantities of decomposing leaves and other materials. And the need to heavily feed my fishes which resided in the aquarium was not that great. They continuously derived supplemental nutrition from the aquarium itself, similar to the "leaf litter only" system I ran a while back with great success.

This is extremely similar to the benefits which flooded grasslands and such provide in Nature.

"Common threads", indeed! 

And of course, it looks totally unique, too.

It's a very different type of "aesthetic beauty" than we are used to. It's an elegant, remarkably complex microhabitat which is host to an enormous variety of life forms.  And it's a radical departure from our normal interpretation of how a tank should look. It challenges us, not only aesthetically- it challenges us to appreciate the function it can provide if we let it.

"Functional aesthetics." Again.

One of the things that we've noticed lately in the hobby, particularly in our sector, is a trend towards more "realistic" aquariums. Not just systems which look like natural environments; rather, systems which are modeled as much after the function of them as the aesthetics.

"Functional aesthetics."

The aquarium looks a certain way because of its function.

A less rigidly aesthetically-controlled, perhaps less "high-concept" approach in the eyes of some- setting the stage for...Nature- to do what She's done for eons without doing as much to "help it along." Rather, the mindset here is to allow nature to take it's course, and to embrace the breakdown of materials, the biofilms, the decay...and rejoice in the ever-changing aesthetic and functional aspects of a natural aquatic system- "warts and all" -and how they can positively affect our fishes.

We're seeing that not only do botanicals, leaves, and alternative substrate materials look interesting- they provide a physiological basis for creating unique environmental conditions for our fishes and plants. We're seeing fish graze on the life forms which live in and among the decomposing botanicals, as well as the botanicals themselves- just like in nature...And we are seeing the influence- aesthetically and chemically- that these materials assert on the aquarium's environmental parameters.

Some of the "next" things that I see our community working on are further explorations into understanding and replicating natural water parameters and what the implications are for our aquariums. I also see more developments in trying to recreate some aspects of natural "food chains" in our BWBS aquariums, by facilitating the growth and reproduction of fungi, microorganisms, and small crustaceans within our botanical "beds" and leaf litter.

It's about expectations and understanding. If you're just looking for a cool aesthetic, that's okay. You simply need to understand what happens to botanicals when they are submerged in they break down, what they do to the appearance and environmental parameters of our tanks. 

It's the era of "Functional Aesthetics"- and yeah, you're right in the thick of things.

The common threads which connect these aquariums is their emphasis of form versus function. Sort of like, "if you set up the tank to work a certain way, it'll look different, too!" 

And with Nature as our guide, we've got a pretty good track to run on!

Stay inspired. Stay excited. Stay busy. Stay engaged. Stay creative...

And Stay Wet.


Scott Fellman

Tannin Aquatics


Scott Fellman
Scott Fellman


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