"Environmental impact..."

In recent months, I've spent a lot of time developing some new ideas for botanical-style aquariums; thinking through iterations, processes, materials, and mental shifts that need to be made as we move forward. Some are pretty radical ones. Others, subtle, incremental steps.

All of them are useful and, in my opinion, potentially very interesting!

Among the numerous concepts that I've been thinking about is how specific botanical materials can impact aquatic habitats in the geographical regions from which they come- and how we might be able to take advantage of this in our aquariums.

Of course, it is perfectly logical to imply that botanicals, wood, and other materials which we ultiize in our aquascapes not only have an aesthetic impact, but a consequential physical-chemical impact on the overall aquatic environment, as well.

Not really difficult to grasp, when you think about it in the context of stuff we know and love in other areas of life...

Wine, for example, has "terroir"- the environmental conditions, especially soil and climate, in which grapes are grown, and that give a wine its unique flavor and aroma... And it's well-known that coffee acquires traits from the soils and climates in which it grows that are similar. Tangible effects and characteristics, which impact the experience we get from them.

And of course,  I can't help but wonder if this same idea applies to our botanicals?

It must!

Yeah, it HAS to. Right?

I mean, leaves come from specific trees, imparting not only tannins and humic substances into the water, but likely falling in heavier concentrations, or accumulating in various parts of rain forest streams or inundated forest floors at particular times of the year, or in specific physical locales with in a stream or river.

And, it's absolutely not out of the question to assume that the leaves, seed pods, etc. on these trees and shrubs have different concentrations of these compounds at different times of the year as well, and that these factors have varying influences upon water chemistry, right?

And of course, when these materials end up in waterways, they provide the fishes which reside in that given area a specific set of physical/chemical conditions, which they have adapted to over time. The same with soils and sediments that accumulate on forest floors and meadows (The Pantanal in Brazil comes to mind here), which have an absolute impact on the aquatic environment when the waters return.

Is this not the very definition of "terroir?"

Yeah, sort of...right? 

Actually, it makes perfect sense.

As we've discussed before, the soils, plants, and surrounding geography of an aquatic habitat play an important and intricate role in the composition of the aquatic environment. They influence not only the chemical characteristics of the water (like pH, TDS, alkalinity), but the color (yeah- tannins!), turbidity, and other characteristics, like the water flow. Large concentrations of botanical materials or leaves become physical structures in the course of a stream or river that affect the course of the water.

And of course, they also have important impact on the diet of fishes...Remember allochthonous input form the land surrounding aquatic habitats? And the impact of humic substances? Yeah, these factors are extremely important in the grand scheme of things.

And of course, I simply can't help but wonder what sorts of specific environmental variations we can create in our aquarium habitats; that is to say, "variations" of the chemical composition of the water in our aquarium habitats- by employing various different types and combinations of botanicals and aquatic soils.

I mean, on the surface, this is hardly a revolutionary idea...

We've been doing stuff like this in the hobby for a while- more crudely in the fish-breeding realm (adding peat to water, for example...), or with aragonite substrates in Africa Rift Lake cichlid tanks, or with mineral additions to shrimp habitats, etc.

Now, this is NOT exactly the same idea as the "biotope aquarium" crowd plays with, IMHO. That's more of a physical and arguably "superficial" attempt at replicating aspects of the natural habitats from which our fishes hail. Very, very cool- but different, I believe, than what we're talking about here.

We can, of course, borrow "mental capital" from the work done in other aquatic endeavours. It's there for the taking, lol.

In the planted aquarium world, for example, it's long been known that soil types/additives, ie;  clay-based aquatic soils, for example, will obviously impact the water chemistry of the aquarium far differently than say, iron-based soils, and thusly, their effect on the plants, fishes, and, as a perhaps unintended) side consequence, the overall aquatic environment will differ significantly as a result.

So, it pretty much goes without saying that the idea that utilizing different types of botanical materials in the aquarium can likely yield different effects on the water chemistry, and thus impact the lives of the fishes and plants that reside there- is not that big of a "stretch", right?

It isn't.

I can't help but wonder what the possible impacts of different leaves, or possibly even seed pods from different areas can have on the water and overall aquarium environment.

I mean, sure, pH and such are affected in certain circumstances - but what about the compounds and substances we don't- or simply can't- test for in the aquarium?  What impacts do they have? Subtle things, like combinations of various amino acids, antioxidant compounds, obscure trace elements- even hormones, for that matter...

Could utilizing different combinations of botanicals in aquariums potentially yield different tangible results for our fishes? You know- scenarios like, "Add this if you want fishes to color up. Add a combination of THIS if you want the fishes to commence spawning behavior", etc.

It sounds a bit exotic, but is it really all that far-fetched an idea?

Absolutely not, IMHO.

I think the main thing which keeps the idea from really developing more in the hobby- knowing exactly how much of what to add to our tanks, specifically to achieve "x" effect- is that we simply don't have the means to test for many of the compounds which may affect the aquarium habitat.

At this point, it's really as much of an "art" as it is a "science", and more superficial observation- at least in our aquariums- is probably almost ("almost...") as useful as laboratory testing is in the wild. Sure, we can test for tannins in the aquairum- but what does it mean? What is a concentration that makes sense for our purposes? What's a "good" number? Is there any correlating test work on these substances being done in the wild aquatic habitats?

Now, I have found some work on ionic and trace element concentrations in some well-known aquatic habitats, but the ability for a hobbyist to test for many of the compounds measured is virtually non-existent at the present time. I can only hope that at some point, detailed hobbyist-level ICP-OES analysis- similar to what is available for reef tanks, becomes available for freshwater hobbyists. That would be a game-changer!

At least at the present time, we're largely limited to making "superficial" observations about stuff like the color a specific botanical can impart into the water, etc. Impact on pH, TDS, etc. is what we have to work with- better than nothing, I suppose! Of course, our home aquarium "field studies" of our fishes in various water chemistry scenarios is useful for our purposes! Even simply observing the effects upon our fishes caused by environmental changes, etc. is useful to some extent.


Of course, not everything we can gain from this is superficial...some botanical materials that we play with actually do have scientifically-confirmed impacts on the aquarium environment; or on fish health, at the very least.

In the case of catappa leaves, for example, we can at least infer that there are some substances (flavonoids, like kaempferol and quercetin, a number of tannins, like punicalin and punicalagin, as well as a suite of saponins and phytosterols) imparted into the water from the leaves- which do have scientifically documented affects on fish health and vitality. 

When we first started Tannin, I came up with the term "habitat enrichment" to describe the way various botanicals can impact the aquarium environment. I mused on the idea a lot. (I know that doesn't surprise many of you, lol...) Now, I freely admit that this term may be interpreted as much a form of "marketing hyperbole" as it is a useful description.

However, I believe that the idea sort of resonates, when we think of the aquarium as an analog for the wild aquatic habitats, and how the surrounding environment- the terroir- impacts the aquatic environment, right?

As we play more and more with the "Urban Igapo" idea of creating a "wet-dry" seasonal cycle replication in aquariums, perhaps this dynamic can be more easily and dramatically understood by hobbyists.

And of course, when it comes to utilizing botanicals and creating more "authentic" blackwater conditions in our aquariums, we hear the interesting stories from fellow hobbyists about dramatic color changes, positive behavioral changes,  rehabilitated fishes, and those "spontaneous" spawning events, which seem to occur after a few weeks of utilizing various botanicals in aquariums which formerly did not employ them.

Sure, these are not carefully-controlled scientific experiments. Likely, a good number of these interesting events and effects could likely be written off as mere coincidences or anecdotal occurrences. However, when it happens over and over and over again in this context, I think it at least warrants some consideration! There must be "something in the water", right?

We're slowly figuring this stuff out.

Yeah, we’re artists at this point. 

And this stuff is really as much of an “art” as it is a “science”, IMHO. 

There is so much we don’t know yet. Or, more specifically, so much we don’t know about botanicals in the context of keeping fishes. We're still largely in an "experimental" phase, and likely will be for some years to come. And that's just fine with me...The "art" is pretty fun and engaging at this point!

We need to tie a bunch of loose ends together to get a really good read on this stuff until we get to the "Dial-a-River” additive stage ("Just add a little of this and a bit of that, and...")

But we're slowly getting there...At least in terms of understanding some of the tangible benefits of botanical use, besides just the aesthetics.

Continued experimentation with different approaches within our botanical-style aquarium obsession is likely to yield more information that will advance the "state of the art." Allowing ourselves to "get out of our own way" and give serious thought to the impacts of things like alternative substrates, and "substrate-centric" aquariums is a really huge avenue for us to explore. We're literally just scratching the surface here.

And it all starts with understanding the impact of...the terroir, right? The impact of the materials that we use on the aquatic environments of our fishes. It's something we've played with for years, but are only recently starting to understand...Separating mere aesthetics from a deeper, possibly more meaningful understanding of Nature as it relates to our aquariums.

Stay observant. Stay resourceful. Stay methodical. Stay curious. Stay dedicated.  Stay creative...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

January 18, 2020

Excellent and interesting point, Peter. And it really gets at the heart of the entire “conundrum” with closed system aquaria of any kind that attempt to replicate a specific biotope…I mean, even within a given biotope, there are variables, and, as you suggest, fishes could avoid those areas which they find to be uncomfortable. It’s interesting! I LOVE the story about the orchid! It’s one of those interesting things that we stumble on now and again in fish keeping that just “clicks!”

SO much we still don’t know; so much to think through and play with! That’s why I find this little game we’re playing with our aquariums so very compelling!

Thanks for sharing!


Peter Ashby
Peter Ashby

January 18, 2020

The thing to bear in mind though is if there is a particular concentration in the water, under a shedding tree for eg then the fishes are at liberty to avoid that area if they do not find it congenial. if we then produce an aquarium with a heavy reliance on one botanical then introduce fish, those fish have no ability to go elsewhere if they do not find it very congenial.

That is not to say that playing around should not happen. I had a dead phalaenopsis orchid and wondering looked up where they lived in the wild. In precisely those places I was trying to recreate. As epiphytes they would absolutely grow and shed obove watercourses. So I added a dried leaf to the aquarium. To my absolute surprise the female lace/pearl gourami went and ate it. The snails ate it and the ancistrus catfish (not biotope compatible but she was born in the tank) also had a nibble.

She also eats mulberry leaves like they’re lettuce so they do not persist in the tank for long. Being passed through fish digestion is one way to get things into the aquarium though.

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