June 05, 2020

Small creatures. A bigger perspective, and a huge impact!

One of the aspects of botanical-style aquariums that we discuss from time to time, but can't bring up enough, is the importance of the "microbiome" of the aquarium environment.

A "microbiome", by definition, is defined as "...a community of microorganisms (such as bacteria, fungi, and viruses) that inhabit a particular environment." (according to Merriam-Webster)

You may not see them- at least, not all of them. However, they are present in almost every aquarium...Especailly our natural, botanical-style aquariums.

Now, sure, every aquarium has a microbiome to a certain extent:

We have the beneficial bacteria which facilitate the nitrogen cycle, and play an indespensible role in the function of our little worlds. The botanical-style aquarium is no different; in fact, this is where I start wondering...It's the place where my basic high school and college elective-course biology falls away, and you get into more complex aspects of aquatic ecology in aquariums.

Yet, it's important to at least understand this concept as it can relate to aquariums. It's worth doing a bit of research and pondering. It'll educate you, challenge you, and make you a better overall aquarist. In this little blog, we can't possibly cover every aspect of this- but we can touch on a few points that are really fascinating and impactful.

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.

Now, one thing that's 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 habitats...so 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 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.

And look at this little gem I found in my research:

"There is evidence that detritivores selectively feed on conditioned leaves, i.e. those previously colonized by fungi (Suberkropp, 1992; Graca, 1993). Fungi can alter the food quality and palatability of leaf detritus, aecting shredder growth rates. Animals that feed on a diet rich in fungi have higher growth rates and fecundity than those fed on poorly colonized leaves. Some shredders prefer to feed on leaves that are colonized by fungi, whereas others consume fungal mycelium selectively..."

"Conditioned" leaves, in this context, are those which have been previously colonized by fungi! They make the energy within the leaves and botanicals more available to higher organisms like fishes and invertebrates!

It's easy to get scared by this stuff...and surprisingly, it's even easier to exploit it as a food source for your animals! This is a HUGE point that we can't emphasize enough.

And of course, the same goes for our buddies, the biofilms.

Biofilms are interesting, in and of themselves. Understanding the reasons they arise and how they propagate can really help us to appreciate them!

We've discussed this before; however, let's revisit the process one more time:

It starts with a few bacteria, taking advantage of the abundant and comfy surface area that leaves, seed pods, and even driftwood offer. The "early adapters" put out the "welcome mat" for other bacteria by providing more diverse adhesion sites, such as a matrix of sugars that holds the biofilm together. Since some bacteria species are incapable of attaching to a surface on their own, they often anchor themselves to the matrix or directly to their friends who arrived at the party first.

These bacteria and fungi are all participants in a rather grand process of nutrient utilization- both in Nature, and in our aquariums. And it all starts with adding botanicals and leaves to our systems. This is absolutely analogous to what happens in Nature.

And that is EXACTLY what we want. Not to give Nature "lip service" as many aquarium hobby movements do. No, we want to embrace Nature in all her glory and diversity. We want to replace our expectations of what we think Nature should look and function like, and simply study, understand, appreciate and support her processes in our aquariums

We need to really step back sometimes and separate ourselves from the sexy (well, to some of us) look of botanical-style aquariums, and really try to grasp the biological diversity that occurs in our tanks! We need to celebrate it- regardless of appearance- and understand how amazing this really is!

The front row seat that we as botanical-style aquarium lovers have is quite unique in the aquarium hobby. In my opinion, no other hobby speciality is poised to study, appreciate, and embrace the vast diversity and process of Nature like we are. It's incredibly exciting and humbling to realize that the mental shifts that our community has taken- going beyond just the aesthetics- and really working with Nature, as opposed to fighting Her- will likely yield some of the most important breakthroughs in the history of the aquarium hobby.

We're glad you're here. We're super proud to be supporters of this new, vital movement to create the ultimate expression of "natural" in our aquairums!

Stay curious. Stay fascinated. Stay diligent. Stay humble. Stay bold. Stay unique...

And Stay Wet.

Scott Fellman

Tannin Aquatics