The race to the bottom...


If you're like me, and you're crazy enough to try to write a new blog post/podcast episode every day, you sometimes need a bit of "help" from your friends. Today's idea came to me in the form of a question I received not long ago from a reader.

It really helped!

Q- Scott, you really place a lot of emphasis on the stuff on the bottom of the aquarium! How does this differ from "active substrates" for planted tanks, and are there other benefits for aquariums that you can gain by using botanicals as the substrate?- J.C., Rockford, IL (USA)

Oh, this is a good one. I can ramble a bit on this!

Let's get to the bottom of things...again.

I really think one of the most "liberating" things we've seen in the blackwater, botanical-style 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, no, he's talking about that "functional aesthetic shit again!"

Yes. Yes I am. 😎

Let's think about the way I look at the substrate of an aquarium.

When you're operating in our "arena", in a strictly aesthetic sense, the bottom itself becomes a big part of the aesthetic focus of the aquarium. 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 botanicals placed upon 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 fact, I dare say that one of the next frontiers in our niche would be an aquarium which is just substrate materials, without any "vertical relief" provide by wood or rocks.

We've tried this before, and it worked out pretty well

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

In fact, some of the more fascinating habitats we'd like to replicate are simply flooded grasslands, such as Brazil's Pantanal, featured in this image by our friend, Tai Strietman. It's essentially a meadow that is covered by seasonal inundation. The only "vertical component" of the scape is the grass and/or low-lying terrestrial plants that resided in the meadow. And of course, texture is provided by the soil and tree roots that might be present in a specific locale.

And some of the other "substrate only" natural habitats are offshoots of streams, or even "vernal pools"- temporary habitats filled with leaves and botanical debris, and little else. These are also very interesting habitats to re-create in a small aquarium. This interesting shot by David Sorry from the Amazon region shows exactly how interesting this unique habitat could is!

And the interesting thing about these features, from a purely aesthetic standpoint, is that they create an incredibly alluring look with a minimum of "design" required on the hobbyist's part. I mean, literally tossing twigs or leaves on the bottom of the aquarium and walking away is the biggest part of your "aquascaping session."

Remember, you can to put together a substrate with a perfect aesthetic mix of colors and textures, but that's about it. We have to "cede" some of the "work" to nature at that point! And certainly, you can build some vertical into your display with  branches and other materials to create the look you like...However, it's super interesting to really develop the substrate area, IMHO.

Once it's in place, nature takes over and the materials develop that lovely "patina" of biofilms and microbial growth, and start breaking down, are moved by fishes, or otherwise slowly redistributed around the aquarium.

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

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

I mean, sure, we've done hardscapes before, with wood and stones dominating the 'scape. However, our tanks have placed far more emphasis on the "functional" aspects of the botanical materials we use.

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 our 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.

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

It's certainly no stretch to call our use of botanicals as a form of "active substrate", much like the use of clays, mineral additives, soils, etc. in planted aquariums. Of course, we're not talking about plants in this context...

Although our emphasis is on creating specific water conditions, fostering the growth of microorganisms and fungi, as well as creating unique aesthetics, versus the "more traditional" substrate materials fostering conditions specifically for plant growth.

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

We've talked about "functional aesthetics" created by botanicals in the aquarium, the potential for additional biological support/filtration (and potentially even denitrification), and it's a big, BIG topic, with lots more to be explored, discovered and deployed in our aquarium...flirting with a "substrate-only"- or "substrate-focused" tank is one of those tantalizing, at first seemingly awkward, yet ultimately transformational little projects we can play with! 

Lots of cool things we can play with. Lots of cool experiments to do.

Stuff like that 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, setbacks...and rewards- for taking this road less travelled.

Enjoy the real "race to the bottom..."

Stay inspired. Stay unique. Stay adventurous. Stay creative. Stay diligent...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




Scott Fellman
Scott Fellman


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