"One person's trash..."

As we move forward into the work of botanical-style aquariums, it seems that we are starting to acquire the skills, mindset, and nuances to advance the "state of the art."

One of the things that we have discussed a lot here and elsewhere is how botanicals begin to break down and decompose, and what their impact on the overall ecosystem of a botanical-style natural aquarium is.

The first thing to think about is that leaves, seed pods, and other botanical materials is that they are more or less "ephemeral" in their nature. As soon as you place these terrestrial materials in the water, they begin to recruit bacterial biofilms, slough off some of their outer tissues, and impart any bound up tannins, organics, and nutrients into the water. 

The biofilms and organic materials become an integral part of the closed ecosystem of the aquarium, and as such, influence the water chemistry and nutrient "load." Now, at first, you'd think to yourself, "Damn, all of this crap can take my water quality South really quickly!" Well, sure, it could- if you add too much, too fast, and are lax on other basic aspects of aquarium husbandry (ie; fish stocking levels, regular water exchanges, filter media replacement, etc.).

If added in a patient, measured manner (particularly in an established, stable aquarium), the bacterial population, the higher organisms (micro crustaceans, etc.), and ultimately, you're fishes, will have the opportunity to multiply and consume the food "by-products" produced by the botanical material as it breaks down. 

And this process, which should make sense to all who have studied the nitrogen cycle and closed aquarium husbandry and management, typically generates more questions to the uninitiated to our concept...It can be a bit counterintuitive- I mean, we're talking about throwing in a bunch of botanical stuff into an otherwise "clean" tank...


Apart from, "What botanicals should I use for a _____________ style setup?" the most common question we receive is ""Do I leave them in or let them break down in my tank?"

And of course, our simple answer is..."It's your call!"

Now, this is an important question. How we answer it- work with it- has fundamental implications for how we operate our blackwater, botanical-style aquariums.

It's as much about your aesthetic preferences as it is about the long-term health of the aquarium. It's a decision that each of us makes based on our tastes, management "style", and how much of a "mental shift" we've made into excepting the transient nature of a blackwater, botanical-style aquarium and its function. There really is no "right" or "wrong" answer here. It's all about how much you enjoy what happens naturally, versus what you can control in your tank.

I tend to favor nature. But that's just me.

I like the idea of leaving materials in my aquariums until they break down completely. Long, long ago, I made that mental shift to a philosophy which says, "Hey, it's okay to have some decomposing stuff and biofilms and...detritus...in your tank. It's natural-looking-and facilitates natural biological functions!"

Now, the caveat here is that I didn't just "give myself permission" to neglect tanks or avoid basic husbandry...no, that wasn't the point. The point is to accept that materials breaking down in our aquariums can provide "fuel" for the biological processes which create long-term stability in a closed system. 

Like any other type of aquarium, a botanical-style system relies on time-honored practices of maintenance, nutrient export, and attention from the aquarist. However, one thing that we have that a lot of types of systems don't is an abundance of potential food sources for a myriad of organisms which reside in our tanks. We are very much creating a little microcosm, and it needs to respect the "checks and balances" which Nature imposes.

And of course, we can't ever lose sight of the fact that we are creating and adding to a closed aquatic ecosystem, and that our actions in how we manage our tanks must map to our ambitions, tastes, and the "regulations" that Nature imposes upon us.

She'll absolutely kick your ass if you don't pay attention to husbandry. I 100% guarantee it. Full stop.

Allowing plants, fishes, shrimp, and bacteria the chance to utilize the decomposing botanicals in their life cycle is an important part of the game, IMHO. Being overly fastidious about siphoning out every speck of dirt or botanical material as it breaks down is "overkill", in my opinion, and can be just as detrimental as over-doing things. 

Nature strikes a balance. Nature thrives on efficiency. When you're adding botanicals to a tank, you're not just doing "aquascaping"- you're laying down the groundwork for the "biological operating system" of your aquarium. As such, you need to think "big picture" here. (That "functional aesthetics" thing again!)

And while we're talking about adding botanicals, from time to time, I need to revisit the "doomsday scenarios" that could occur. Now, it's important to note that the very few "disasters" we've been told about typically happened under a few situations or combinations of them:

1) The aquarist did not prepare anything as instructed

2) A significant amount of botanicals relative to water volume was added all at once to a long-established aquarium

3) A significant amount of botanicals was added to an established tank in a very short period of time (like within a couple of days)

Now, again, there are always anomalies, but these situations are almost "set ups" for some types of issues. Typically, what happens is you'd see fishes gasping at the surface for oxygen, which becomes rapidly depleted by the addition of a large influx of materials breaking down, which can also overwhelm the biological filtration capacity of a tank. 

Usually, the "rescue" consists of increased vigorous aeration and a succession of water changes, removing the botanicals, use of activated carbon, etc...the typical "emergency fixes" for problems of this nature.

The best preventative is to go slowly. To consider impacts.

The reality is, adding botanicals to your tank and using them, replacing them regularly, etc, is no more "dangerous" than anything else we do as aquarists. You simply need to go slowly, apply common sense, follow our prep instructions, and observe your tank carefully.

Is that a guarantee of success? Of course not. Could you have some weird combination of events, local water composition, overly sensitive fishes, etc. which could give you a disastrous outcome? Of course. 

Be careful. Be responsible...And be thoughtful.

And of course, the stuff breaks down, it creates...detritus.

What exactly is this stuff?

We've been told for decades that it's bad freakin' news. Well, on the surface, the definition of detritus does seem a bit...well, dangerous:

"detritus is dead particulate organic matter. It typically includes the bodies or fragments of dead organisms, as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose or remineralize the material." (Source: The Aquarium Wiki)


It's one of our most commonly used aquarium terms...and one which, well, quite frankly, sends shivers down the spine of many aquarium hobbyists. And judging from that definition, it sounds like something you absolutely want to avoid having in your system at all costs. I mean, "dead organisms" and "fecal material" is not everyone's idea of a good time, ya know?

Yet, when you really think about it, "detritus" is an important part of the aquatic ecosystem, providing "fuel" for microorganisms and fungi at the base of the food chain in tropical streams. In fact, in natural blackwater systems, the food inputs into the water are channeled by decomposers, like fungi, which act upon leaves and other organic materials in the water to break them down. 

And the leaf litter "community" of fishes, insects, fungi, and microorganisms is really important to these systems, as it assimilates terrestrial material into the blackwater aquatic system, and acts to reduce the loss of nutrients to the forest which would inevitably occur if all the material which fell into the streams was washed downstream!

That sounds all well and good and grandiose, but what are the implications of these processes- and the resultant detritus- for the closed aquarium system?

Well first off, let's admit that the stuff  just doesn't look that nice to most of us, and that's partially why the recommendation for a good part of the century or so we've kept aquariums is to siphon it the hell out! And that's good advice from an aesthetic standpoint- and for that matter, from a husbandry standpoint, as well. Excessive amounts of accumulating waste materials can lead to increased phosphate, nitrate, and other problems, including blooms of nuisance algae. Emphasis on the word "excessive" here...(which begs the question, "What is "excessive" in this context, anyways?)

Most hobbyists don't have the time, inclination, or optimized system set up to take advantage of a small accumulation of this stuff. However, with the importance of detritus in creating food webs in wild leaf litter communities, which we are now replicating in aquariums, could there actually be some benefit to allowing a little of this stuff to accumulate? Or at least, not "freaking out" and removing every single microgram of detritus as soon as it appears?

I think so. Really.

Is this another one of those long-held "aquarium truisms" that, for 90% of what we do is absolutely the correct way to manage our tanks, but which, for a small percentage of aquarists with the means, curiosity and inclination to experiment, could actually prove detrimental in some way?

Okay, I know that now a bunch of you are thinking, "This guy IS nuts. Letting detritus accumulate in an aquarium is bad news. A recipe for problems- or worse. And not only that, he has no idea of the implications of what he's suggesting."

Well, as far as the first part of your thought- Yeah, I could be a bit "crazy." On the other hand, I think I do have some idea of the implications of what I'm postulating here. First off, remember, I'm not suggesting that everyone throw away their siphons and just allow shit (literally!) to accumulate in their aquarium substrate in the interest of creating a "food web."  

No sir.

What I am curious about is if there is some benefit in a botanical, blackwater system, of encouraging a bit more fungal and microbial growth, utilizing, among other things, the organic detritus that inevitably is produced in a well-managed. well-populated aquarium.  I mean, if you're doing water changes and removing uneaten food, dead fishes, aquatic plant leaves, etc., you're already significantly reducing the "food inputs" available to the organisms on the low end of the food chain, right?

In a typical aquarium, well-maintained with regular water changes and removal of detritus, our fishes are almost 100% dependent upon us to provide food, right?

There's usually very little for them to forage on in most aquariums, other than the occasional algal film (assuming they're herbivorous) or particle of uneaten food. Creating militant, "near sterility" in our aquariums, which do at least superficially resemble true ecosystems, might actually be detrimental in some way, right? I mean, you're removing one component of a natural cycle and replacing it with a high-octane, "shotgun approach" substitute of just taking everything out.

Can it be said that this actually Creates, perhaps (?) an unnecessary "dependency" of sorts on this human intervention, right? At the very least, are we actually making the management of aquariums more challenging by sort of "fighting" nature, and simply not thinking this through all the way? Doesn't nature, if left to her own devices, tend to keep excesses of all sorts more-or-less in check? 

I'm not suggesting to abandon all husbandry practices, of course. Just suggesting we think about the "hows and whys" just a bit more...perhaps with a different viewpoint.

So, perhaps- maybe- Is there just some merit in the idea of leaving a bit of detritus in the system- say, in the leaf litter bed, to help "fuel" the fungal and microorganism growth that forms the basis of our little ecosystems? I mean, think of some possible benefits to our aquariums. Having a more complete assortment of fungi and microorganisms could lead ultimately to a more stable, more efficient aquarium, right?

Yeah, I realize that an aquarium is not an "open system", with huge volumes of water throughput, replenishment by rain, and pulses of materials being added to the system. 

However, we do replicate some of these processes- via water exchanges, media replacement, etc.

So, why don't we do more?

By, like, well, letting some stuff break down in situ. Allowing a bit of detritus accumulate. Letting the fishes and other organisms utilize it as food.

Yes. Food. And...maybe a biological support system, which can process nutrients, nitrate and phosphate, via bacterial growth. So, it makes sense to let some of this material remain in our tanks, right?

If you're not wiping out a percentage of the ecosystem's primary decomposers and  food sources weekly with ultra-intense maintenance, wouldn't there perhaps be some advantages? And don't a lot of young fishes consume "infusoria" as a part of their initial diet? Wouldn't it make sense to have larger populations of some of these organisms available to our fishes at all times in the aquarium to supplement our artificial diets? Could the fry-rearing system of the future be a tank with a big bed of decomposing leaf litter and a terrestrial soil substrate?


Much like what we've done in the reef aquarium world over the past few decades, I think that those of us who play in this little niche of the freshwater world need to look at our systems more "holistically"- and consider each component of the aquarium an integral part, fulfilling valuable roles.

Much like the "deep sandbags" and live rock of the reef aquarium world, can a deep leaf litter/botanical bed and lots of botanicals in one of our aquariums foster beneficial organisms which can accomplish...denitrification- among other things?

And, in such a deep layer of leaves or botanicals, is it advisable to replace them on a more frequent basis to prevent maintenance liabilities? For that matter, are decomposing leaves on this scale a "maintenance liability?"

Could they be considered a "carbon source"- the freshwater equivalent of "biopellets"- to fuel beneficial bacterial growth within the system, creating excellent nutrient processing capacity... as opposed to being some sort of "destroyer" of water quality?

Could we be missing something?

Could it actually be that a deep layer of botanicals/leaves is actually a key to creating a biologically stable aquarium, once you reach a certain depth, if the overall husbandry of the tank is good? Maybe? Now, I've never had any issues with a relatively small, open layer of leaves in any of my tanks (we're talking 1"-3" /2.54-7.62cm) or so. I just wonder if the dynamic changes significantly- for the better- or worse- when you approach a foot of depth in an aquarium?

Something we'll just have to see, I suppose!

At the very least, looking at our botanicals and leaves and the resulting decomposition, detritus, and organics as a "fuel" for beneficial processes is something worth doing, IMHO.

Time for more work. Time to look at this stuff more seriously. It's not time to be afraid, dismiss things outright because "they" all say you shouldn't....

Yeah, it may indeed be true that the old expression about "...one person's trash is someone else' treasure..." could be part of our "mantra" as we move forward. We might very well treasure our decomposing leaves and the associated biotic that they bring.

I believe so.

Stay curious. Stay grounded. Stay diligent. Stay progressive. Stay excited. Stay logical...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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