August 05, 2020

An idea that's been floating around in my head...

As we go further and further into the world of botanical-style aquariums; deeper into unusual niches and ideas, it's refreshing and inspiring to turn towards our mentor, Nature- to find out how to replicate them in the aquarium.

You're probably either mildly amused, or completely fed up fed up with our obsession about leaf litter in aquariums, or maybe- just maybe- just as geeked-out as we are about 'em, right?

Yeah, I kinda figured it'd go down something like that.

We make it a point to scour scientific papers and scholarly research articles for topics relevant to our obsession. The other day, I stumbled on a cool paper about...floating leaf litter banks!

Fascinating natural aquatic structures found in Amazonia, which are extremely enticing!

(Photo from Carvalho, et al.)*

Oh, you know where this is going...

So imagine, if you will, a "classic" submerged leaf litter bed in Amazonia, composed of a variety of leaves, branches, twigs, seed pods, and other botanical materials...yet floating on the surface of the water! What you get is a fairly deep layer of plant materials colonized by fishes and other creatures, which forage on the macro invertebrate life and insects found in these assemblages. Biologists call this an "ephemeral" habitat, as it is transitory or temporary as it slowly breaks apart.

Okay, so it slowly breaks apart over months and months...or maybe longer. Yet it's not permanent...

According to one study I read, eventually, most of the organic debris is deposited on the stream bottom or drifts downstream until it becomes trapped by a variety of natural obstacles.

These floating, or partially submerged litter beds either accumulate on tree branches hanging from the riparian vegetation, or they remain anchored by fallen tree trunks and branches near the water surface, where they may form a really deep layer of materials.

After reading about these assemblages, I found this to be an irresistible niche habitat to replicate in the aquarium! It seems to be the freshwater analog of the Sargassum "forests" of the Caribbean and Tropical West Atlantic! Little oases of life in the vast, open water.

According to one study, these floating or partially submerged leaf litter banks either accumulate among the branches of riverside vegetation during the high water season, gradually floating downstream, or stay anchored in place by fallen tree trunks and other large materials, ultimately forming a more "traditional" submerged leaf litter bed.

It was discovered that many fish species associate with these floating litter banks for the entire wet season, and one of the reasons they stay put is because their food sources are there, too! In fact, a species of "water bug", Weberiella rhomboides, is found almost exclusively in these floating banks, attracting large numbers of insectivorous fishes, like characins, catfishes, knifefishes, and others.

In other words, these stands of floating leaves and botanicals are literally a "moveable feast", a veritable "floating fish buffet", if you will! The fish populations found in these environments are typical of what you'd expect to find in a more "static" leaf litter environment.

What fishes would you expect to find in this cool niche? Well, it's kind of a "who's who" of blackwater, leaf litter zone dwellers, some of which are very familiar to us as hobbyists- for example, characins like Hemmigramus species, Moenkhausia species, the killifish Rivulus ornatus, and of course, cichlids, including a number of Apistogramma, Crenicichla, Hypselecara, and the much-loved Mesonauta festivus, to name a few.

And then there is that most ubiquitous of leaf-litter-dwelling characins...one which I've almost never seen in the hobby, but I see everywhere in leaf litter population studies, Elachocharax pulcher! I've been told that it shows up occasionally, but being a leaf litter dweller, it probably evades capture by local fishers, and it's cryptic coloration makes it less than exciting (read that, fucking dull) for any but the most geeked-out aquarists...like me and, hopefully, you!

Okay, rad. Lots of fish choices...That was never the issue, right?

The bigger next question is, how the hell would you recreate a facsimile of this environment in an aquarium? (second only to, "Would you want to?")

The answer is, "Of course!"

Now, I admit I haven't tried this idea myself yet, but being such an enabler, I want to encourage someone with an extra tank and a healthy fascination with this type of niche to try it if I don't get to it first!

Just how would you do this? Well, I envision the process as pretty straightforward. I'd personally employ a wide aquarium, for a nice sense of perspective. Likely a "standard" height or deeper. I'd utilize a substrate of fine sand, with a smattering of twigs (like oak twigs) and some smaller leaves, like Yellow Mangrove.

And of course, I'd use some leaves for the surface. I'd select a bunch of smaller leaves, like Guava, Yellow Mangrove, and a smattering of Live Oak leaves, with a few twigs thrown in for good measure.

Of course, we'd recommend a little prep- perhaps just a few minutes of steeping in boiling water- or just pour over some boiling water to help clean them and perhaps just soften the outer cuticle layers. The idea is not to saturate them to the point where thy'll sink right off the bat, but to at least give them a good cleaning.

And of course, they'll float for a while, until they're completely saturated.

Ohh, this is getting really good...

I'd imagine that you'd probably filter this tank with an outside power filter or canister filter with the return positioned in such a way as to minimally disturb the surface. You'd essentially be creating a diverse assemblage of leaves, just like you would if you were doing a "conventional" leaf-litter display (Ha! I love that- a "conventional leaf litter display"- look how far we've come...).

Now, eventually, some of this stuff would sink, or be trapped below the floating "matrix", and you'd end up with materials on the bottom...Okay...cool! It would transition naturally to a more common "botanicals-on-the-bottom" display. So this is essentially an "ephemeral display"- transitioning from a "floating leaf litter bed" to a submerged leaf litter aquarium! Or is it a "transitional ephemeral display?"

Whatever you want to call it- it's an amazing idea for an aquarium, I think.

Twigs, leaves, flowers, terrestrial and floating aquatic plants...Nature provides no shortage of inspiring features to incorporate into such a display.

Of course, you could probably keep it going by replacing the leaves and such as you would anyways, right? And as the wood becomes submerged, you'd "let it do it's thing", and/or replace/add new pieces.

I would wager that no one has ever really tried this in an aquarium before- at least, not intentionally. If you have, I would love to see it! If you haven't, I'd love to see you do it!

Shit, now I'm convincing myself to do it!

I do have an empty tank lying around...