Decomposing Botanicals and the case for keeping them in...

A common question we're asked by neophyte "tinters" is if they should leave their leaves and botanicals in their aquariums until they break down.

And my simple answer, based on my personal experiences is..."Yes!"

Of course, that deserves some explanation, so here you go:

We love the idea of decaying leaves, botanicals, wood. We love the influence that these materials have over the aquatic environment. It's earthy, organic, and natural. 


As in what nature looks like. Functions like…

When I first started playing with blackwater tank almost two decades ago, I began wondering why these types of tanks were seen in the hobby as a "novelty"; why every "blackwater biotope" tank shown on the forums was greeted with both accolades for being different, and polite, but reserved discussion about the aesthetics being a bit "odd." About the difficulties and "maintenance liabilities" of such a tank.

"Messy." "Dirty." “Dingy."

I heard those terms all the time in the context of blackwater aquairums. I get it. On the surface, this looks like you're always one step from disaster and mess..

And of course, that's no different from any type of tank we play with, when you think about it.

I love the fact that these types of systems need to be managed; they're not a static, "set-and-forget-", aquascaping-contest-type of aquarium. They're  every bit as dynamic as a "traditional" high-tech, "Nature-style" planted aquarium, reef tank, or good old fashioned community tank. You need to monitor, observe, react, tweak, etc. Bioload, pH, and other environmental parameters dance together to make it work...just like any other aquarium.

And the “mess?”

"Mess" is actually a vehicle to propel us in different aquascaping/experimental directions. It actually is the embodiment of Amano's wabi-sabi philosophy, which embraces the transience of nature- and celebrates it. It appreciates and understands the beauty in the ephemeral aspects of nature.

It requires some study, appreciation, and yes- mental adjustments.

And the biofilms, which make their appearance on our botanicals after a few weeks of submersion?


They are not only typically harmless in aquariums, they are utilized as a supplemental food source by a huge variety of fishes and shrimps in both nature and the aquarium. They are a rich source of sugars and other nutrients, and could prove to be an interesting addition to a "nursery tank" for raising fry if kept in control. Like, add a bunch of leaves and botanicals, let them do their thing, and allow your fry to graze on them! Don''t believe me? Ask almost any shrimp keeper-they'll "sing the praises" of biofilm for the "grazing" aspect!

And the botanicals themselves, as they break down, serve as "fuel" for the growth of fungi and microorganisms...which, in turn, provide supplemental food for our fishes. 

Pieces of leaves and botanicals fall to the bottom of the aquairum, and form a bed of…detritus. Yes, I said detritus. In the aquarium world, we've long vilified the stuff as “a destroyer of water quality”; an impediment to successful aquariums. And the reality is that, in a well-managed aquarium, "detritus" is an essential food source for many organisms and plants. 

Like anything else in a closed system, if it's not allowed to accumulate unchecked, I personally believe its benefits for the animals we keep far outweigh any perceived disadvantages of having it present.

I know that uneaten food and fish poop, accumulating in a closed system can be problematic if overall husbandry issues are not attended to. I know that it can decompose, overwhelm the biological filtration capacity of the tank if left unchecked. And that can lead to a smelly, dirty-looking system with diminished water quality. I know that. You know that. In fact, pretty much everyone in the hobby knows that.

That's not the issue, really, IMHO.

The issue is that we as a hobby have sort of heaped detritus into this "catch-all" descriptor which has an overall "bad" connotation to it. Like, anything which is allowed to break down in the tank and accumulate is bad.

I'm not buying it.

Why is this necessarily a "bad" thing?

Check out he definition of detritus: 

"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)

I mean, even in the above the definition, there is the part about being "colonized by communities of microorganisms which act to decompose or remineralize…"


It's being processed. Utilized. What do these microorganisms do? They eat it...They render it inert. And in the process, they contribute to the biological diversity and arguably even the stability of the system. Some of them are utilized as food by other creatures. Important in a closed system, I should think.

It's not all bad, right?

And it's fueled by stuff like decomposing leaves and botanicals.

So, yeah- I let my leaves and botanicals stay in my aquariums until they completely break down, only removing them if they become an annoyance (ie; every time a fish moves, a pile of the shit gets stirred up, or its accumulating on my driftwood, etc.)- but it never gets to that point in my tanks.

It’s being processed. Used. Colonized. Consumed. 

It's not an excuse for sloppy husbandry, or neglecting the removal of offensive materials. However, it IS a sort of acceptance of the fact that "stuff happens" in nature- and in aquariums- and that many of these things are simply not worth getting upset about. I mean, if you have an aquarium with brown water, and substrate dominated by decomposing leaves and softening botanicals, it shouldn't come as any surprise, right?

Decomposition is not something to freak out about. Rather, it's something to celebrate. Life, in all of its diversity and beauty, still needs a stage upon which to perform...and you're helping provide it, even with material changes taking place daily.

Again, it's a real mental shift that we as hobbyists have to make. Sure, there will always be a lot of people that don't like the look of brown water, decomposing leaves, biofilms and fungi in their aquariums. It's a radically different look than what we've come to accept an aquarium "should" look like for the better part of the century.

Initial responses by the uninitiated who see a botnaical-botanical-style tank for the first time are  usually filled with stuff like, “Damn, that tank is kind of dirty, huh?” 

Now, I certainly cannot fault anyone for not enjoying the aesthetics of our aquariums...It's not for everyone. However, an interesting observation I've made over the years by both "uninitiated" hobbyists and non-hobbyists upon seeing a blackwater, botanical-style aquarium for the first time is an amazing appreciation for "how natural" they look. 

I’ve heard this over and over an over again! 

The real the key here is that pace- and an understanding that the materials that we add need to be added-and replaced- at a pace that makes sense for your specific system. An understanding that you'll have a front row seat to the natural processes of decomposition, transformation, decay...and accepting that they are part of the beauty of this style of aquarium, just like they are in nature.

So, consider keeping those botanicals and leaves in your aquarium until they become…detritus. 

You just might enjoy watching the process.

Stay bold. Stay curious. Stay open-minded. Stay engaged…

And Stay Wet.

Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


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