Streams: The "jumping off" point for your botanical obsession...

Of all of the natural water courses found in the tropical regions of the world, few hold as much allure for me as streams.

The definition of a "stream" is: "...a body of water flowing in a channel or watercourse, as a river, rivulet, or brook..."

And of course, these little bodies of water flow through jungled areas, where they're bound to pick up some leaves, twigs, and other plant parts as they wind along their path. Leaves, the "jumping off point" of our botanical obsession, form a very important part of these stream habitats.

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?

It's logical, right? And it's also interesting, because, as we know, fishes and their food items tend to aggregate in these areas, and embracing the "theme" of a litter/botanical bed or even wood placement,  in the context of a stream structure in the aquarium is kind of cool!

In nature, the rain and winds also effect the depth and flow rates of many of the waters in this region, with the associated impacts mentioned above, as well as their influence on stream structures, like submerged logs, sandbars, rocks, etc. Stuff gets redistributed constantly. Much in the way we might move a few things around now and again during maintenance! Perhaps we could aggregate botanicals in part off ur aquariums, rather than "coat" the whole bottom...


Well, rather than covering the whole bottom of your tank with leaves, would it be cool to create some sort of hardscape structure- with driftwood, etc., to retain or keep these items in one create a "framework" for a long-term, organized, specifically-placed litter bed. You could build upon, structure, and replace leaves and botanicals in this "framework"- like, indefinitely...sort of like what happens in the "meanders!"

How would fishes react when presented with a deep litter bed in part of the aquarium; would they prefer to reside there? Or would they simply forage there and stay in the more open areas of the aquarium? Would the spawn there? Probably some fry would seek shelter there, right?


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!
I'm thinking cool niche biotope aquarium here...
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 Nanostimus, 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!  

So, protection from predators- survival- is a powerful motivation for fishes to seek out these different habitats. Now, granted, in the aquarium we are almost guaranteed NOT to keep predators and prey in the same tank (at least, not for long-term display purposes!), but is there not something to be gained by replicating such environments? 


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

And of course, in the aquarium, we're all about fostering of natural behaviors...Even if they are not "necessary" for survival. I can't hope but wonder if providing some of these more specific environmental conditions (in concert with stuff like water chemistry and the presence of stuff like leaves, wood, etc.) could facilitate greater possibilities for spawning, long-term health, and greater lifespan?

Maybe. I think it's entirely possible. I think that the tropical streams of the world- that "jumping off point" for our botanical obsession, hold many lessons for us as aquarists.
I think we need to look beyond just the cool looks of the natural habitats from where our fishes hail, and focus on the attributes which comprise their function. We need to understand why fishes are attracted to certain habitats, and apply these lessons into our aquariums. A successful aquarium is not just a pretty look.  It's a "complete package" sort of thing.

And THAT is a beautiful thing, right?

Stay curious. Stay resourceful. Stay diligent. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Scott Fellman
Scott Fellman


Leave a comment