Beyond the microbiome...

Many of us are even moving beyond just the pretty look of the botanical-style aquarium, and moving into a deeper stage of understanding how our aquariums function as miniature ecosystems.

Part of the whole "game" of the botanical-style aquarium is understanding how, why and what happens to terrestrial materials when they're placed in water.

Nature has been working with terrestrial materials in aquatic habitats for eons.

And Nature works with just about everything you throw at her!

She'll take that seemingly "unsexy" piece of wood or rock or bunch of dried leaves, and, given the passage of time, the action of gravity and water movement, and the work of bacteria, fungi, and algae- will mold, shape, evolve them into unique and compelling pieces, as amazing as anything we could ever hope to do...

Yeah, one thing that's very unique about the botanical-style approach is that we tend to accept the idea of decomposing materials accumulating in our systems. We understand that they act, to a certain extent, as "fuel" for the micro and macrofauna which reside in the aquarium, and that they perform this function as long as they are present I the system.

I have long been one the belief that if you decide to let the botanicals remain in your aquarium to break down and decompose completely, that you shouldn't change course by suddenly removing the material all at once. 

The point is, our aquariums, much like the wild habitats we strive to replicate, are constantly evolving, accumulating new materials, and creating new physical habitats for fishes to forage among. New food sources and chemical/energy inputs are important to the biological diversity and continuity of the flooded forests and streams of the tropics, and they play a similar role in our aquariums.

We add leaves and botanicals periodically, not just for an aesthetic "refresh", but for a "re-charge" of the biome within our tanks. This is a fascinating spect of the botanical style aquarium. It facilitates the cycle of growth, nutrient accumulation, and decomposition. It becomes not only part of our practice, but it's part of the "system" we are trying to facilitate.

I'm fascinated by the "mental adjustments" that we need to make to accept the aesthetic and the processes of natural decay, fungal growth, the appearance of biofilms, and how these affect what's occurring in the aquarium. It's all a complex synergy of life and aesthetic.

And we have to accept nature's input here.

Nature dictates the speed by which this decomposition process occurs. We set the stage for it- but  Nature is in full control.

And that's perfectly okay! 

Nature can control. Nature can stabilize. Nature can admonish us...However, Nature can also provide.

We've talked a lot about allochthonous input- food which comes from outside the aquatic environment- such as insects, fruit, seeds, etc. You know, stuff which literally falls from the trees! However, there is also a significant amount of food which our fishes can obtain which occurs within the aquatic habitat itself. 

This is something that we, as lovers of the botanical-style aquarium, are well-suited to embrace. And of course, I"m utterly fascinated by the concept of food production within our botanical-style aquariums! Yes, food production. If you really observe your tank closely- and I'm sure that you do- you'll see your fishes foraging on the botanicals...picking off something.

I've noticed, during times when I've traveled extensively and haven't been around to feed my fishes, that they're not even slightly slimmer upon my return, despite not being fed for days sometimes... 

What are they eating in my absence?

Well, there are a number of interesting possibilities.

Perhaps most interesting to us blackwater/botanical-style aquarium people are epiphytes. These are organisms which grow on the surface of wood, botanicals, 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 fave 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.

The biocover consists of stuff like algae, biofilms, and fungi. Although most animals use leaves and tree branches for shelter and not directly as a food item, grazing on this epiphytic growth is which occurs on them is very important.

I am of the opinion that a botanical-style 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!

It's well known that in many habitats, like inundated forests, 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 one again that a blackwater/botanical-style aquarium could be an excellent sort of "nursery" for many fish and shrimp species! 

And of course, it goes beyond even that...

Because of the very "operating system" of our tanks, which features decomposing leaves, botanicals, soils, roots, etc., we are able to create a remarkably rich and complex population of creatures within them.

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 soem supplemental nutritional value for our fishes, and perhaps most important- nutrient processing- a self-generating population of creatures that compliment, indeed, create the biodiversity in our systems on a more-or-less continuous basis.

True "functional aesthetics", indeed!

Another important part of our aquarium microcosms are fungi.

Yeah, you heard me. Fungi.

Fungi have evolved to use a lot of different items for food. Some are decomposers living on dead organic material like leaves. These are the guys we typically encounter in our botanical-style aquariums' leaf litter/botanical beds!

Fungi reproduce by releasing tiny spores that then germinate on new and hospitable surfaces (ie, pretty much anywhere they damn well please!). These aquatic fungi are involved in the decay of wood and leafy material. And of course, when you submerge terrestrial materials in water, growths of fungi tend to arise.

Anyone who's ever "cured" a piece of aquatic wood of almost any type for your aquarium can attest to this!

Fungi tend to colonize wood because it offers them a lot of surface area to thrive and live out their life cycle. And cellulose, hemicellulose, and lignin- the major components of wood and botanical materials- are degraded by fungi which posses enzymes that can digest these materials! Fungi are regarded by biologists to be the dominant organisms associated with decaying leaves in streams, so this gives you some idea as to why we see them in our aquariums, right?

And of course, fishes and invertebrates which live amongst and feed directly upon the fungi and decomposing leaves and botanicals contribute to the breakdown of these materials as well! Aquatic fungi can break down the leaf matrix and make the energy available to feeding animals in these habitats.

If there is one aspect of our botanical-style aquariums which fascinates me, it's the way they facilitate the natural processes of life- specifically, decomposition.

We use this term a lot around here...What, precisely does it mean?

de·com·po·si·tion- dēˌkämpəˈziSH(ə)n -the process by which organic substances are broken down into simpler organic matter.

A very apt descriptor, if you ask me! 

We add leaves and botanicals to our aquariums, and over time, they start to soften, break up, and ultimately,decompose. This is a fundamental part of what makes our botanical-style aquariums work. Decomposition of leaves and botanicals not only imparts the substances contained within them (lignin, organic acids, and tannins, just to name a few) to the water- it serves to nourish bacteria, fungi, and other microorganisms and crustaceans, facilitating basic "food web" within the botanical-style aquarium- if we allow it to!

Decomposition of plant matter-leaves and botanicals- occurs in several stages.

It starts with leaching -soluble carbon compounds are liberated during this process. Another early process is physical breakup or fragmentation of the plant material into smaller pieces, which have greater surface area for colonization by microbes. 

Does the liberation of carbons, sugars, etc. in our systems impact the water quality of our aquariums? Of course it does! And yeah- you need to monitor water quality in your aquariums regularly, to establish what's "baseline" for your system.

It's just common sense.

It's important to remember that leaves and such are simply not permanent additions to our 'scapes, and if we wish to enjoy them in their more "intact" forms, we will need to replace them as they start to break down. 

This is not a bad thing.

The real added "bonus" for leaving the leaves and botanicals "in situ" until they completely break down is that they will help facilitate the production of supplemental food resources within the aquarium.

I have personally experienced this time and time again, by setting up botanical-style systems for the expressed purpose of providing supplemental food for the resident fishes. I've done this with adult fishes, and I've actually "reared" (well, Nature dod the work) many fish fry to maturity by setting them up in heavy botanical-stocked systems with little to no supplemental feeding. The fishes feed on the fungal growths and biofilms, as well as the organisms which are associated with them...just like in Nature.

This, to me, is extremely exciting.

And it's really as much of a mental shift as it is anything else- like so much of what we do with botanical-style aquarium systems. The willingness of us to really look to Nature as more than just an inspiration for making cool-looking aquariums. Rather, an approach which understands that our botanical-style aquariums require  us to step back and observe what happens in wild aquatic habitats, and realizing that the same processes occur in our aquariums.

Natural materials, submerged in water, processed by a huge diversity of organisms, working together. A microbiome. All of these things are beautiful, natural, and incredibly important in our closed systems if we give them a chance.

It seems that we spend so much time resisting the appearance of some of this stuff and focusing on it's removal, that it's not given a chance to present its "good side" -which there most definitely is. And, the fact is that these life forms and processes appear in wild environments for a reason.

The botanical-style aquarium that we play with is perhaps the first of it's kind in the hobby to really say, "Hey, this is just like nature! It's not that bad!" And to make us think, "Perhaps there is a benefit to all of this."

Think beyond the look. Think beyond the basic "function." Think beyond the microbiome.

Stay bold. Stay progressive. Stay studious. Stray thoughtful. Stay curious. Stay educated...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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