May 24, 2020

The fishes know it...

As hobbyists, we spend enormous amounts of time, money, and energy attempting to create the ideal aquascape for our fishes. And, let's face it; pretty much no matter how we 'scape a tank- no matter how much- or how little- thought and effort we put into it, our fishes will ultimately adapt to it.

They'll find the places they are comfortable hiding in. The places they like to forage, sleep and spawn. It doesn't matter if your 'scape consists of carefully selected roots, seed pods, rocks, plants, and driftwood, or simply a couple of clay flower pots and a few pieces of egg crate- your fishes will "make it work."

It's what fishes do. It's what they've done for eons.

And as aquarists, what we've collectively and admirably done for a century or so is try to create optimum conditions for the fishes we keep. This includes both the physical-structural and chemical environment. We've talked a lot about the chemical environment, vis a vs our botanical-style/blackwater aquariums. Today, let's just think for a few moments about the physical-structural environment we create for our fishes, and why.

When we're planning an aquascape, we spend an enormous amount of time selecting the right materials- rocks, wood, botanicals, etc., to get the right "feel" to our 'scape. This is a most enjoyable and interesting phase of an aquarium build, for sure- but take yourself out of the "I'm-gonna-enter-THIS-ONE-in-the-aquascaping-contest-and-place high" mindset for just a second, and put yourself into the mindset of...a fish.

Yup. Think like a fish for a second.

I mean, sure, I'll bet that fishes like living in those insanely cool 'scapes you see in all of the contests; however, those are mainly designed and constructed for the pleasure of humans, right? They're designed for our tastes. Specifically, for human judges, who evaluate a design-based on a set of specific criteria. "Iwagumi" looks really cool, but I'd hazard a guess that you won't find many of these "submerged Stonhenge" features in the natural streams and rivers of the world.

I'm just gonna go out on a limb and make that speculation...

So what about considering just how the fishes interact with the aquascape you create?

My suggestion?

Again: Think like a fish a bit more.

Really. It might be kind of fun-and educational- to think about where your fishes are found in the natural streams, lakes, and rivers they come from...and "work backwards." I mean, fisherman have been doing this for eons...why not fish hobbyists?

It makes perfect sense, because, well, we have a pretty fair collective understanding of how fishes interact with their environment, don't we?

I think so.

Let's look at some of the features in natural bodies of water where fishes are commonly found...this might give you some insight into how to incorporate them into an aquascape.

I need not discuss flooded forests all that much, because we've pretty much written more on this topic than just about anything over the years...Suffice it to say, my obsession with these unique habitats is well-founded; they are filled with amazing features, ranging from tree trunks to root tangles, to submerged terrestrial plants and leaf litter- all of which we can replicate in the aquarium in dramatic fashion.

And then there are flooded Pantanal meadows- essentially grasslands with low scrub brush and plants, which are flooded seasonally, providing a rich and diverse underwater habitat for a variety of fishes. These habitats, equally as engrossing as the flooded forests, are seldom replicated in the aquarium, fore reasons that I cannot quite understand. Perhaps it's the "dirty" aesthetic which has thrown us off? Regardless, the fishes make use of the submerged grasses and vegetation for foraging and spawning among.

And of course, there are many features of streams and rivers that fishes LOVE to congregate in...Think about how you might consciously incorporate some of them into your next aquascape!

First off, a few "sweeping generalities."

Fishes tend to live in areas where the food and protection is, as we've talked about previously. Places that provide protection from stronger current, and above-and below-water predators. Places where they can create territories, interact, spawn and defend themselves.

Bends in streams and rivers are particularly interesting places, because the swifter water movement will typically carry food, and the fishes seem to know this. And if theres a tree branch, trunk, or a big rock (or rocks) to break up the flow, there will be a larger congregation of fishes present.

So, the conclusion here is that, at least in theory, if you design your 'scape to have a higher "open water" flow rate, and include some features like rocks and large branches, you'll likely see the fishes hanging in those areas...

In situations where you're replicating a faster-flowing stream environment, think about creating some little "rock pockets", perhaps on one side of the aquarium, to create areas of calmer water movement. Your fishes will typically orient themselves facing "upstream" to catch any food articles that happen on by. So, from a design perspective, if you want to create a cool rock feature that your fishes will likely gather in, orienting the flow towards it would be a good way to accomplish this in the aquarium.

Among the richest habitats for fishes in streams and rivers are so-called "drop-offs", in which the bottom contour takes a significant plunge and increase in depth. These are often caused by current over time, or even the accumulation of rocks, leaves, and fallen trees, which "dam up" the stream a bit. (extra- you see this in Rift Lakes in Africa, too...right? Yeah.)

Fishes are often found in drop offs in significant numbers, because these spots afford depth (which thwarts the hunting efforts those pesky birds), typically slower water movement, numerous "nooks and crannies" in which to forage, hide, or spawn, and a more restive "dining area" for fishes having to contend with strong currents. From an aquascaping perspective, this gives you a lot of cool opportunities.

If you're saddled with one of those seemingly ridiculously deep tanks, a drop-off could be a perfect subject to replicate. And there are even commercially-made "drop-off" tanks now! With a little observation of natural habitats, some planning, and a bit of creativity, there's no limit to how effective a recreation of this habitat you could accomplish!

Overhanging trees are common in jungle areas, as we've discussed many times. Fishes will tend to congregate under trees for the dimmer lighting, "thermal protection", and food (insects and fruits/seeds) that fall off the trees into the water. And of course, if you're talking about a "leaf litter" or botanically-influenced aquascape, a rather dimly-lit, shallow tank could work out well.

Lots of leaves, pieces of wood in a "tree-root" like configuration, and some seed pods would complete a cool look. For a cool overall scene, you could introduce some riparian plants to simulate the bank as well. A rich habitat with a LOT of opportunities for the creative 'scaper!

Why not create an analogous stream/river feature that is known as an "undercut?" Pretty much the perfect hiding spot for fishes in a stream or river, and undercuts occur where the currents have cut a little cave-like hole in the rock or substrate material near the shore.

Not only does this feature provide protection from birds and other above-water predators, it gives fishes "express access" to deeper water for feeding and escaping in-water predators!

Trees growing nearby add to the attractiveness of an undercut for a fish (for reasons we just talked about), so subdued lighting would be cool here. You can build up a significant undercut with lots of substrate, rocks, and some wood. Sure, you'd have some reduced water capacity, but the effect could be really cool.

Leaves, the "jumping off point" of our botanical obsession, form a very important part of these stream habitats. They fall from the trees, accumulate in the water, and work their biological magic.

It is known by science that the leaf litter and the community of aquatic animals that it hosts is, according to one study, "... of great importance in assimilating energy from forest primary production into the blackwater aquatic system."

It also functions as a means to preserve the nutrients that would be lost to the forests which would inevitably occur if all the material which fell into the streams was simply washed downstream. The fishes, crustaceans, and insects that live in the leaf litter and feed on the fungi, detritus, and decomposing leaves themselves are very important to the overall habitat.

In the aquarium, leaf litter and botanicals certainly perform a similar role in helping to sequester these materials.

As we've talked about before briefly, another interesting thing about leaf litter beds is that they actually have "structure" and even longevity. In several studies I read on the subject, the accumulations of leaves in various streams are documented to have existed in the same locations for years- to the point where scientists actually have studied the same ones for extended periods of time.

Some litter beds form in what stream ecologists call "meanders", which are stream structures that form when moving water in a stream erodes the outer banks and widens its "valley", and the inner part of the river has less energy and deposits silt- or in our instance, leaves.

There is a whole, fascinating science to river and stream structure, and with so many implications for understanding how these structures and mechanisms affect fish population, occurrence, behavior, and ecology, it's well worth studying for aquarium interpretation! Did you get that part where I mentioned that the lower-energy parts of the water courses tend to accumulate leaves and sediments and stuff?

There are other interesting structures in streams which we would be well served to study and replicate in our aquariums. Streams typically feature two interesting biotopes that we haven't really discussed in much detail here, and both of which are quite profoundly impacted by the seasonal rains:

Pools, with slower current and a substrate covered mainly by deposits of leaf litter, detritus and driftwood; and "rifﬂes" (defined as shallow sections of a stream with rapid current and a surface broken by gravel, rubble or boulders), with a moderately-fast-ﬂowing current and mostly sandy bottom with tree roots, driftwood pieces, and small rocks and pebbles. (ohh...home to Darter Characins!

These "riffles" are considerably more significant in the wet season, when the obvious impact of higher water volumes are present. In the Amazon, for example, you'll find an unexpected abundance of some species familiar to us as hobbyists in these "riffles." Species like Pyrrhulina brevis, Hyphessobrycon melazonatus, and Hemigrammus of various forms, and even some Nanostomus, and the killie Rivulus compressus.

Interesting "factoid": Some scientists have postulated that the higher presence of nocturnal predators in the pools adjacent to the more active riffles might increase the number of species that seek refuge in the riffles to avoid them! And Rivulus, which usually live in more intermittent pools along the stream edges, outside the main stream channels, are normally found at night in these rifﬂes!

Reduction of stress. Indeed, survival. That's pretty important in the wild...so I'd imagine it's equally as important in the aquarium.

In the end, design and build the aquascape that makes you happy.

However, if you're trying to create something a bit different and perhaps a bit more true to nature, you might want to take a little "field trip" to a nearby stream, river, creek, lake, etc., where fishes and other aquatic animals reside, and observe things from the perspective of how they interact with the features of the environment.

You should "get outside" and do this once in a while! You'll definitely leave with some inspiration, ideas, and just maybe, a slightly different perspective on aquascaping than you've previously had!

Gaining a fresh perspective and new inspiration for your hobby is never a bad thing! So, "thinking like a fish" isn't such a bad idea, is it?

Yeah, the fishes know it. You should, too.

Stay fascinated. Stay inspired. Stay creative. Stay curious. Stay unique....

And Stay Wet.

Scott Fellman

Tannin Aquatics