December 12, 2018

Fast water. Solid botanicals. Interesting concepts.

When we think of interesting ideas for aquascapes, we often have a particular fish or group of fishes in mind. It's the "traditional" way aquarists have developed aquarium schemes for a century or more.

Sometimes, we are interested in fishes from niches that require a little more research and foresight into their needs; we need to contemplate what materials to use that would more authentically "accessorize" their world!

Lately, I've been sort of interested in the ecology of streams with more water movement than the typical inundated forest floors that we tend to model our aquariums after. They are very interesting from a variety of standpoints- in particular, the "structure" that they encompass.

Current in wild streams effects the underwater "topography," with stream structures, like submerged logs, sandbars, rocks, etc. These structures, larger and heavier than say, leaves- still move around a lot as the result of the current, regularly changing the "aquascape"...Much in the way we might move a few things around now and again during maintenance!

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, are fascinating habitats. Ohh...And they're home to Darter Characins! I'm thinking cool niche biotope aquarium here!

And interestingly, you'll find an unexpected abundance of some other species familiar to us as hobbyists in these "riffles." Species like Pyrrhulina brevis, Hyphessobrycon melazonatus, the Hemiancistrus sp."L128" and Hemigrammus of various forms. And even some Nanostomus, and the killie Rivulus compressus!

I find these populations compelling, because we tend to associate a lot of these little fishes with sluggish water and more static environments, not areas exposed to greater current and movement.

And the overall idea of keeping an aquarium replicating such a habitat with a fair amount of current is not at all outside of the "concept" of a botanical-style approach. It's all about the concentration, diversity, and size of the materials used.

Which of our botanicals would you use in an aquarium configured to replicate such a habitat? I'd be inclined to use (in addition to stones of various types), "heftier" botanicals, like Cariniana Pods, "Jungle Pods", Kielmeyera Pods, Mokha Pods, Perhaps a "Monkey Pot" or two, and some "Sky Fruit" Pods. Oh, and Indian Catappa Bark pieces can really tint the water nicely, in addition to providing the streamed floor aesthetic!

With regards to wood, I think in the type of habitat the fish comes from, you'd want something that simulates either a tangle of roots pushed downstream by the current (like Spider Wood or Senggani Root), or maybe something smooth and "log like" in configuration.

Chemically, it's rather interesting to note that streams with more significant current are known to have levels of dissolved phosphorus and nitrogen present in quantities sufficient to support moderate to high biomass of fishes-even under what we might define as 'pristine" conditions. They will, of course, have higher levels of dissolved oxygen than streams or bodies of water with less current. These are sort of "biological "givens" when considering this type of habitat.

And where there are fishes- there are food sources...

In a study I found of the feeding habits of fishes from fast-moving streams in Brazil, it was noted that the diets of most of the resident species were (aquatic) insectivorous (35.7%), followed by detritivores (21.4%), benthivores (14.2%), omnivores (14.2%), herbivores (7.1%), and piscivores (7.1%). This is interesting, because almost all of the nutrition derived by the resident fishes is from the streams themselves, as opposed to from allochthonous sources (Foods from the surrounding habitats, like fruits, flying insects and ants, etc.- Remember those?)

This is intriguing, and not what I would expect. I'd tend to think that, with greater current, you'd see less "in situ" generation of food. Yet, these streams seem to be full of surprises, don't they?

So much to consider...More than we could even hope to cover in a teaser blog like this...My initial research yielded so many angles to explore! Hopefully, maybe- discussion of this habitat will inspire a few of you to do some further research and perhaps develop your own aquarium based on one of these "fast water" habitats?

Stay inspired. Stay curious. Stay diligent. Stay excited...

And Stay Wet.

Scott Fellman

Tannin Aquatics