Article © Julian Dignall, uploaded March 08, 2009.
An uncommon find that I kept a few years ago now is Scleromystax macropterus, the species name meaning long finned — and then some - and it was this feature that made the fish initially appealing to me. Adult males of this species are readily identified because the dorsal and especially pectoral fins are elongated up to five times their normal size — to the point the fish look very ungainly indeed. This development isn't a given, it may not occur and it is most obvious on the dominant male of a group. To my mind it reminds me of antler development in stags. That these long fin rays are similarly deployed amongst competitive males may be taking this speculative observation too far however.
Keep an eye out for this fish though, it's quite possible with the shift in export patterns out of Brazil of late, that the exporters will turn their attentions to the Atlantic coast drainages of Sao Paulo state and south. Furthermore, Scleromystax macropterus is found to live alongside S. barbatus in some of its range, here we find it in sub tropical climes, yet still in blackwater. Here it rarely will encounter aquatic plants, but rather finds refuge in shady overhanging or partially submerged vegetation at the side of wood and leaf strewn streams with water the colour of tea. It's reported in the wild it prefers a higher vantage point in the water column than S. barbatus.
In the aquarium then, it's important to keep this fish under pH 7 and relatively cool. It's also important to give them more space than perhaps you would afford a typical Corydoras group, dominant males are surprisingly aggressive. Perhaps this in part explains why this species has not yet bred in captivity. I think also the unusual set-up (from the point of view of comparison with a typical Corydoras breeding set-up) it would require soft, acidic water, kept cool, power filtration and possibly floating plants (to replicated submerged vegetation), perhaps optionally leaf litter and good lighting to penetrate the tea coloured water. Put altogether, that's not what most Corydoras breeders have in their average tank although breeding successes with other Scleromystax suggest it's maybe just a matter of dedicating some time to such a project.
Copyright information for the images used in this article can be found on the species' full Cat-eLog page.
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