Beyond the the sexy looks...A "deep dive" on "functional aesthetics"- Again.

I'm sort of continuing on a theme here today...part of my "Magnum Opus" on "land meets water" and how we can replicate and benefit from this in our aquarium work...As you know, the past week or so, I've been going on and on and on about the interesting biological niches which arise when terrestrial environments become inundated with water during the rainy season.

We have discussed many aspects of these unique habitats and how we as aquarists can replicate aspects of them to create unique and highly functional aquariums for the fishes that we keep. SPOILER ALERT: You can have a great looking, almost "artistic" aquascape and still embrace and mimic natural functions.

Yeah, we've talked a lot about them, and we've seen many of you go on to successfully recreate some of them. And they are as beautiful as they are functional. And the "functional" aspect is, in my opinion, as compelling- if not, even more so- than the mere sexy aesthetics of these habitats. Just thinking about the dynamics, fish adaptations, and components of these systems can really get your creative juices flowing!

(I give huge props to my friend, Tai Strietman, for really pioneering this with his heavy use of palm fronds in aquariums...)

And one of the most compelling aspects of these tropical habitats is how they "power" the food webs which our fishes benefit from. I think that this is something we as aquarists have overlooked for decades, and with more emphasis than ever being placed on the "look" of the aquarium, it's even more possible that the amazing function of the natural habitats we love is not getting enough attention from hobbyists when we think how we're gonna fill that empty glass box.

And of course, we need look no further for inspiration than Nature.

In the seasonally flooded forests and plains of Brazil, for example, plants grow and take up nutrients from the sediments during the dry "terrestrial phase", store them in their tissues and leaves, and release them into the water where they begin to decompose after these habitats flood.

After the inundation, fishes may directly feed on the organic materials from these terrestrial plants, such as fruits, flowers, leaves, seeds, detritus, and bark. In fact, science has documented over 200 species (primarily larger characins and catfishes) in Amazonia alone which are specifically adapted to feed on fruits, nuts, submerged grasses, and other terrestrial plant materials!

(Well, you're not likely to keep the huge Pacu, Colossoma macropomum, but it's a classic example of a "fruit eater!" Pic by Rufus46, used under CC BY-SA 3.0)

Many other fishes which reside in these flooded forest areas feed mainly on insects; specifically, small ones, such as beetles, spiders, and ants from the forest canopy. These insects are likely dislodged from the overhanging trees by wind and rain, and the opportunistic fishes are always ready for a quick meal!


Interestingly, it's been postulated that the reason the Amazon has so many small fishes is that they evolved as a response to the opportunities to feed on insects served up by the flooded forests in which they reside! The little guys do a better job at eating small insects which fall into the water than the larger, clumsier guys who snap up nuts and fruits with their big 'ol mouths! 

Some species of fishes specialize in detritus.

As we know by now, decomposing leaves are the basis of the food chain, and the detritus they produce forms an extremely important part of the food chain for many, many species of fishes. Some have even adapted morphologically to feed on detritus produced in these habitats, by developing bristle-like teeth to remove it from branches,tree trunks, plant stems, and leaf litter beds. 

Of course, it's not just the fishes which derive benefits from the terrestrial materials which find their way into the water. Bacteria, fungi, and algae also act upon the nutrients released into the water by the decomposing organic material from these plants. Aquatic plants (known collectively to science as macrophytes) grow in or near water and are either emergent, submergent, or floating, and play a role in "filtering" these flooded habitats in nature.

Terrestrial trees also play a role in removing, utilizing, and returning nutrients to the aquatic habitat. They remove some nutrient from the submerged soils, and return some in the form of leaf drop. 

Interestingly, studies show that about 70% of the leaf drop from the surrounding trees in the igapo habitats occurs when the area is submerged, but the bulk of it is shedded at the end of the inundation period. The falling leaves gradually decompose and become part of the detritus in the food web, which is essential for many species of fishes. This "late-inundation leaf drop" also sets things up for the "next round" - providing a "starter" of nutrients !

Flood pulses in these habitats easily enable large-scale "transfers" of nutrients and food items between the terrestrial and aquatic environment. This is of huge importance to the ecosystem. As we've touched on before, aquatic food webs in the Amazon area (and in other tropical ecosystems) are very strongly influenced by the input of terrestrial materials, and this is really an important point for those of us interested in creating more natural aquatic displays and microcosms for the fishes we wish to keep.

This "classic" aquascape by our good friend, Cory Hopkins, utilizing a matrix of leaves, is one of my favorite aesthetic interpretations of this habitat...and it happens to be supremely functional as an aquarium, as well! I think it's a "prototype" for many of us to follow, merging looks and function together adeptly and beautifully.

Study this one...

Now, I think at least part of the reason why we're seeing success with utilizing botanicals in our aquariums is that fish are instinctively "programmed" to utilize many of these materials as both feeding substrates and as food items in and of themselves. (NEWS FLASH: "Pellets and flakes" are NOT part of their natural diet...)

The addition and replenishment of leaves and other botanical materials which we execute in our tanks definitely mimics, at least to some extent, the processes which occur in these habitats which transfer food and nutrients into the aquatic habitat.

And with the ability to provide live foods such as small insects (I'm thinking wingless fruit flies and ants)- and to potentially "cultivate" some worms (Bloodworms, for sure) "in situ"- there are lots of compelling possibilities for creating really comfortable, natural-appearing (and functioning) biotope/biotype aquariums for fishes.

Ever the philosopher/ muser of the art of aquaristics, I sometimes fear that the burgeoning interest in biotope aquariums at a contest level will result in the same sort of "diorama effect" we've seen in planted aquarium contests. In other words, just focusing on the "look" (which is cool, don't get me wrong) yet summarily overlooking the reason why the habitat looks the way it does and how fishes have adapted to it...and considering how we can utilize this for their husbandry, spawning, etc.

I'm sure it's unfounded, but the so-called "nature aquarium" movement seems to have, IMHO, completely overlooked the real function of nature, so there is some precedent, unfortunately. I hope that "biotopers", who have a lot of awareness about the habitats they are inspired by, will at least consider this "functional/aesthetic" dynamic that we obsess over when they conceive and execute their work. 

It should go beyond merely creating the "look" of these systems to win a contest, IMHO. Rather, we should also focus on the structural/functional aspects of these environments to create long-term benefits for the fishes we keep in them. That's a real "biotope aquarium" in my book.

Leaves, detritus, submerged terrestrial plants- all have their place in an aquarium designed to mimic these unique aquatic habitats.  You can and should be able to manage nutrients and the bioload input released into our closed systems by these materials, as we've discussed (and executed/demostrated) here for years.  The fear about "detritus" and such "crashing tanks" is largely overstated, IMHO- especially with competent aquarium husbandry and proper outfitting of a tank with good filtration and nutrient control/export systems in place.

If you're up to the challenge of attempting to replicate the look of some natural habitat- you should be a competent enough aquarist to be able to responsibly manage the system over the long term, as well.

Ouch, right?  Hey, that's reality. Sorry to be so frank. Enough of the "shallow mimicry" B.S. that has dominated the aquascaping/contest world for too long, IMHO. You want to influence/educate people and inspire them? Want to really advance the hobby and art/science of aquarium keeping? Then execute a tank which can be managed over the long haul. Crack the code. Figure out the technique. Look to Nature and "back engineer" it. These things can be done. 

There are many aspects of wild habitats that we choose to replicate, which we can turn into "functionally aesthetic" aquarium systems. Let's not forget the trees themselves- in their submerged and even fallen state! These are more than just "hardscape" to those of us who are into the functional aesthetic aspects of our aquariums.

The trees present in flooded forest habitats actually benefit fishes and aquatic life forms when they fall. Upon the return of the inundating waters, these fallen trees become an important part of the aquatic habitats, providing multiple benefits.  A fallen tree wedged into a stream bottom provides shelter from the currents. The tree trunk changes the flow pattern of the stream to create eddies which may bring in food and wash away fine silt, allowing formation of gravel beds and the accumulation of leaves and fallen botanical materials. 

Foraging areas are created, in which fishes may find insects, small crustaceans, and fruits and such which come from the terrestrial environment. They provide spawning locations for fishes, and shelter for fry to develop and avoid predators.

Although it's possibly impractical for many aquarists to obtain really large branches and such to simulate these submerged tree trunks, it would be a most interesting aquascape feature if you could source larger, thicker pieces to recreate this fascinating microhabitat in your aquarium! And entire community of fishes could be developed around (literally) one large branch win a modest-sized aquarium. Toss in a bunch of leaf litter and some botanicals- and- bam! Instant functional biotope!


Well, almost...You've got the look down. Bring on the function! Encourage some biofilms, algae, and other epiphytic material to colonize the branch/trunk, and then you're on your way to a functional representation of this unique habitat!

So much to talk about, study, and interpret here.

So many unique and compelling aspects of the flooded forests of South America and elsewhere that I know will unlock the secrets of many unique and beautiful fishes which we keep in our aquariums. By providing functional biotope aquariums, we're really setting the stage for what I really feel is the ultimate evolution of aquarium keeping:  Creating aquariums which replicate, as realistically as possible, the look and function of the habitats that we are fascinated by.

Making a "mental shift."

It's a fun and fascinating journey, that will not only yield greater understanding of our fishes, but of the precious and fascinating environments from which they come. And a greater appreciation for the functions and vulnerabilities of these wild ecosystems means that we'll be in a better position than ever as aquarists to call attention to the perils that they face. And when we inspire non-aquarists to understand and learn more about this stuff- the planet wins.

Take the time to go beyond the sexy look. Because you'll find that the function is every bit as fascinating and inspiring as those looks. 

Stay studious. Stay fascinated. Stay curious. Stay resourceful. Stay generous. Stay diligent. Stay obsessive!

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

August 24, 2020

Hi There!

I think you’re referring to the palm frond?



August 23, 2020

On the second photo is a great leaf on the right side, coming from above. Wich plant is that?

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