The smallest allies...

In the botanical-style aquarium, we embrace so many previously under-appreciated and seldom-discussed  (in aquarium circles, anyways) aspects of Nature. None to me is more profound than the way in which we as an aquarium movement have come to appreciate the "microbiome"- defined as a community of microorganisms (such as bacteria, fungi, and biofilms) that inhabit a particular environment.

In our case, the environment is our botanical-style aquariums.

And that's a fundamental thing for us- "recruiting" and nurturing the community of organisms which support our aquariums. In fact, one could safely assert that the whole basis of the botanical-style aquarium is the very materials- botanicals, soils, and wood- which comprise the "infrastructure" of our aquariums. Not only do the botanicals create a physical and chemical environment which supports these life forms, it allows them to flourish and support the life forms above them. 

It all starts with bacteria.

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.


And there are other bacteria which we feel will become even more and more important in botanical-style/blackwater/brackish aquairums:

Enter Rhodopseudomonas palustris.

This is an amazing species of what biologists call Purple Non-Sulfur Bacteria (PNSB). 

PNSB consume carbon/nutrients in anaerobic environments, thereby competing with microbes that produce toxic metabolites (e.g. hydrogen sulfide). Unlike nitrifying and denitrifying bacteria, they are capable of performing photosynthesis. In addition, they have been demonstrated repeatedly to possess strong probiotic properties that promote the health of diverse aquatic species.

PNSB is found in freshwater, marine and brackish environments (in the water column, the sediments and even in the guts of animals such as corals). This highly adaptive photosynthetic bacterium balances nutrient cycling in all types of aquatic and terrestrial systems. This bacterium is an efficient biodegradation catalyst in both aerobic and anaerobic environments.

Like nitrifying bacteria, PNSB metabolize ammonium and nitrite and nitrate. And they're not just important to the nitrogen cycle. They're also capable of aerobic organoheterotrophy - a process of removing dissolved organics from the water column- just like other microbes!

They're the basis of our latest products, "Culture" and "Nurture'- giving you the biological advantage you need for a successful, biologically diverse botanical-style aquarium.


PNSB are useful for their ability to carry out a particularly unusual mode of metabolism: anaerobic photoheterotrophy. In this process, they consume organic wastes while inhabiting moderately illuminated and poorly oxygenated microhabitats (patches of detritus, leaf litter beds, shallow depths of substrate, deeper pores of expanded clay media, etc.). By competing with other anaerobes such as methanogenic archaeans and sulfate-reducing bacteria for food, these voracious "sludge-eaters" significantly reduce the production of toxic byproducts such as methane and hydrogen sulfide!

PNSB have been used to remediate water quality in highly intensive aquaculture operations for many years. They are increasingly being used to amend soils (particularly soils burnt by chemical fertilizers) in horticultural applications. Their probiotic qualities serve to suppress disease in numerous cultured species.

PNSB absolutely love living as epiphytes on aquatic plants! Specifically, they consume organic waste products that are secreted by the plant. And the plants love them back! PNSB fertilize host plants with their surpluses of fixed nitrogen.

And, perhaps of major interest to those who play with aquatic plants, PNSB is also known to form direct, beneficial associations with the root systems of both terrestrial and aquatic plants!


Ultimately, as they are consumed by bacterivores (protozoa, rotifers, copepods, sponges, etc.). PNSB pass essential biomatter (proteins, vitamins and pigments) along the food chain.

The food chain...As in, "helping to a establish a food chain" in our aquariums. An amazing, fascinating, possibly game-changing embrace of biology in our aquariums.

Food chains. Food production from within the aquarium and its closed ecosystem.

Food production?

Yes, food production.

I mean, it's not really a crazy idea, right? For decades in aquariums, fishes- or more specifically, fish fry- have found sustenance in aquariums, poking around plants and leaves and such as they hide from predators, often hanging on until we net them out to a rearing tank.  I'm thinking about the deliberately overgrown "jungle tanks" of my childhood...

And in the botanical-style aquarium, it's even more obvious, as you see adult fishes doing the same thing. Yeah, if you really observe your tank closely- and I'm sure that you do- you'll see your fishes foraging on the botanicals and wood...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... 

And of course, I've shared with you ad nauseam the deliberate aquariums I've set up to test this theory.

What are they eating in my absence?

Well, there are a number of interesting possibilities.

Well, bacteria and biofilms, for one thing. And then, there are fungi.

Yeah, you heard me. Fungi.

"THOSE guys again?"

Yup. THOSE guys.

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.

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.

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, 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 some 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!

We're really excited to be introducing "Culture" and "Nurture"- products which we feel will have a profound influence on the way we start, maintain, and evolve botanical-style aquariums naturally.

In my opinion, no other hobby speciality is poised to study, appreciate, and embrace the vast diversity and process of Nature like we are in the botanical-style aquarium community.

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.

And it starts by embracing new ideas, old concepts, and different applications...It starts by embracing the smallest allies...

Stay creative. Stay resourceful. Stay enthralled. Stay excited...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


1 Response

Joshua E Morgan
Joshua E Morgan

October 22, 2020

Cool! When will either of these products become available? And would they work in a highly acidic (PH 4-5) environment? (I understand that a lot of common bacteria run into problems at such low PH values)

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