Density. Diversity. Function.

When we think of streams and rivers, we probably think of flowing water, sandy bottoms; maybe a few branches...

And, while it's quite true that there are certainly many habitats which fit that description, there are numerous aquatic habitats where fishes reside are simply sluggish, small, branch-leaf-and-tree-trunk-choked pools and such.

Yeah, it's true.

The crystal-clear, swift-moving water is not always home to as large a variety of fishes and other aquatic organisms as these more placid, densely-packed bodies of water are. Have you thought much about how "clogged" with materials some of the natural habitats we intend to imitate in our tanks actually are?

It's kind of interesting to consider, and I've done a little "field work" over the years, as well as some "internet safaris", exploring some of the interesting habitats where our fishes come from, and I've frequently been surprised just how much "stuff" is in the water.

And of course, there is a strange "disconnect" with our interpretation of Nature, and what is really out there.  It makes me think about our aquascapes, and how we are seemingly always concerned about having the "appropriate" amount of "negative space"- at least from an artistic perspective.

I mean, from an aquascaping point of view, I suppose that's quite understandable. And, I would imagine that there is a sort of immediately obvious perception that  having an aquarium that's not densely-packed with materials is somehow more sustainable, healthier, etc. from a practical management standpoint.

Like, it's easier to maintain an aquarium that's more "open."

Or, is it?

Sure, you can easily get a siphon hose into a more open tank. You can keep detritus in suspension where it can be removed more easily-if that's your thing, of course. You know my thoughts on "detritus..."

On the other hand, if you've made that "mental shift" to accepting a more natural-looking- and functioning aquarium, the amount of material you have in the tank makes little difference. You simply adjust your husbandry practices to accommodate the physical "configuration" of the aquarium and go about your business!

Educating yourself about the realities of natural habitats, rather than strictly modeling our aquariums after other aquariums, can open you up to numerous examples of how these environments foster numerous life forms successfully.

When you take into account the materials that accumulate in smaller streams, igarapes, flooded meadows, and swamps, a surprisingly large amount of botanical materials, ranging from tree branches/trunks to leaves and such, accumulates and takes up physical space in the aquatic habitat.

Now, not only do these materials take up water volume and physical space- they serve to direct flow, create other hydrodynamic features, etc. More important, they also accumulate/sequester nutrients and food sources for the organisms which reside in these habitats.

In the aquarium, a larger volume of say, driftwood, rocks, and botanicals will not only impart the oft-mentioned chemical affects into the water, they will similarly channel flow, create territories, and offer areas of visual interest. Well-managed systems which are densely-packed with wood and botanical materials can create surprisingly dynamic, ever-evolving displays.


This is no doubt analogous to the seasonal evolutions of underwater landscapes in Nature, as waters recede after the rainy season, leaving a more densely-packed assemblage of materials in a given area.

To get a better perspective on this, look at the rain forest floor in tropical regions, such as Amazonia. After all, this is what is left during the dry season, and gives you some idea of the eventual "topography" of the underwater landscape when the rains return. 

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, for example- is the evolution of our most compelling environmental niches. The water levels in the rivers rise significantly. often several meters, and the once dry forest floor fills with water from the torrential rain and overflowing rivers and streams.

The Igapos are formed. 

Flooded forest floors. Yeah, I talk about this habitat incessantly. 

The formerly terrestrial environment is now transformed into an earthy, twisted, incredibly rich aquatic habitat, which fishes have evolved over eons to live in and utilize for food, protection, and spawning areas.

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

I can't tell you how amazing this type of habitat is to replicate in the aquarium. It challenges our aesthetic tastes, our skills at managing closed systems, and our ability to understand the benefits of having all of this stuff present in our tanks.

Now, I'm not telling you that you should fill your tanks to the rim with wood, seed pods, leaves, and rocks (although it sounds like a cool idea, doesn't it? LOL). I AM suggesting that you look into the interesting aesthetic and physical affects you can create with a more "dense" scape. Attempt to understand the function and benefits of such a configuration. 


We've already touched on some of the benefits above; analogous to those found in the natural habitats they attempt to represent, and this is increasingly obvious to all of us who play with botanical-style aquariums.

Now, the one of the immediate "downsides" most hobbyists who are unfamiliar with our practices will jump on is, "Hey, more 'stuff' in the water means...less water can't have as many fishes in your tank." Absolutely. Sure. On the other hand, less water volume means you could host fewer fishes...and lower population densities of fishes could actually serve to create a more visually engaging display!

Not only will there be functional and environmental benefits as a result of lower fish populations- you'll probably find some aesthetic ones, as well.

Now, I remember back in the 1980's through the early 2000's, in the reef aquarium side of the hobby, people were obsessed with the concept of "live rock" as a "filter medium", and the prevailing wisdom was that you needed "x" amount of rock per given volume of water in a reef tank...and it was quite a bit...And  of course, the best way to achieve this recommended quantity was to create a literal "wall of rock", something that I have railed on personally for years in my writings and presentations.

It looked pretty crazy.

So, I'd be a bit hypocritical if I was  suggesting a "wall of botanicals" and such; however, I think it would be interesting to play with higher densities of wood and botanicals in some displays. To encourage areas of interest. Yes, fascinating details which encourage the observer to really study the aquarium in a more focused way.

In Nature, all of the botanical material- fallen leaves, branches, seed pods, and such create the biological "operating system" for the aquatic environment.  Soils dissolve their chemical constituents- tannins, and humic acids- into the water, enriching it. Fungi and micororganisms begin to multiply, feed on and break down the materials. Biofilms form, crustaceans reproduce rapidly.  Fishes are able to find new food sources; new hiding areas to spawn.

Life flourishes.

Let's get back to the "practical" aspects again.

There are some keys to maintaining aquarium filled with materials like decomposing leaves and botanicals. We know this by now; it's become part of our "best practices..." You definitely need to do regular maintenance. You don't want to overstock...I mean, common sense stuff. However, in a tank filled with considerable organic material, "slight overstocking" and poor general husbandry can be problematic. 

It's about husbandry and perspective...

And it's about accepting the fact that the leaves and other natural materials are part of the ecology of the tank, and that they will behave as terrestrial materials do when submerged:

They'll break down and decompose. They'll form the basis of a surpassingly complex food chain, which includes bacterial biofilms, fungi, and minute crustaceans. Each one of these life forms supporting, to some extent, those above...including our fishes.


When you think of the botanical materials not so much as "hardscape props", but as dynamic biological components of a closed microcosm, it all makes a bit more sense. And the more material that is present in the system, the greater the "fuel" available for microbial growth to "power" the system.

And when we add/remove/supplement more leaves and botanicals, and allow others to fully break down in our tanks, we are totally mimicking the natural processes which occur in streams and rivers around the world. 

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

And the biofilms and algal growths which appear on our leaves and botanicals-just as they do in the wild habitats we mimic- provide not only a degree of "biological functionality" for our systems, but an evolving aesthetic as well.

Embrace these things- don't fear them.

Understand that the real "designer" of our botanical-style aquaecapes is Mother Nature herself.

We just set the stage.

So- set the stage, and enjoy the random, compelling, and ever-evolving work of art that is the blackwater/botanical-style aquarium. Started by you. Evolved with the steady hand of Nature.

Look, I adore minimalist stuff...abosolutely. However, I'd think it would be interesting (and entirely authentic to Nature) to play with a more complex, "heavy-handed" scape once in a while. Not just for their interesting aesthetics, mind you.


Where it gets really interesting is in a larger aquarium, with a population of smaller fishes dwelling in such a 'scape. For example, imagine the allure of a tank, heavily "choked" with thin wood branches (Mangrove, Manzanita or "Spider Wood" are what I'm thinking), some larger seed pods, bark, and leaves.

By selecting smaller fishes like Tetras, Apsitos, Boraras, Guaramis, Badis, Corydoras, etc., you could maximize the impact by having a fairly high number of fishes in an aquascape that offers a lot less open area, encouraging the fishes to engage in more natural behaviors, like swimming through, and foraging among the dense wood and botanical areas.

If you stock with fishes like Elachocharax, for example- that are known to inhabit more densely packed areas of streams and such, or very specific areas like leaf litter zones, you can create a very unique and engaging display in which the fishes won't be immediately evident to the observer.

As with the "jungle" planted tanks I adore so much, the densely stocked botanical-style aquarium encourages the observer to take the time to "linger" and "discover" the fishes flitting in and out of the hardscape...

Like in any botanical aquarium, a more densely-packed one will require thoughtful, but not excessive maintenance. You'll simply need to feed carefully, stock thoughtfully, and adhere to the typical tenants of aquarium keeping. There is very little that is actually more difficult to manage about this type of tank than any other, when you understand its dynamics.

Like in any other display, a more densely packed one will find its way, developing over time into an intriguing, engaging display that will become a constantly-evolving, highly engaging, and oddly refreshing aquarium.

The appeal of this interesting aesthetic, and the practical benefits may or may not be immediately obvious to you. However, I encourage you to consider an aquarium like this for your next project.

The good news is that, if you find that you prefer a more "open" scape, you can simply remove wood, botanicals, etc., until you hit the aesthetic that appeals to you. And even that, in itself is not unlike the natural processes of current, tidal movements, etc. which "re-arrange" the natural ecosystems all the time!

In the end, turning once again to the incredible, almost infinite "portfolio" of inspiration which Nature provides seems to always provide will steer you in the right direction. If you look at enough natural aquatic systems, you'll no doubt be struck by some habitat that speaks to you, motivates you to replicate it in some way...and to share your work with others.

With the precious natural environments subject to many external forces, perhaps one of the most significant steps we can take to help preserve them is to help others appreciate them by modeling an aquarium after them. 

The natural beauty of an unusually "dense" aquarium like the one's we're discussing here may just motivate non-aquarists to take a greater interest in helping preserve and protect these precious natural ecosystems.

An that's the biggest "win" of all!

Until next time...

Stay curious. Stay inspired. Stay adventurous. Stay unique. Stay excited...

And Stay Wet.


Scott Fellman

Tannin Aquatics




Scott Fellman
Scott Fellman


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