Taxonomy & naming
Schistura cataracta was described by the Swiss ichthyologist Maurice Kottelat in 1998 and has held that combination ever since — there is no evidence of an older "Nemacheilus cataracta" or other prior name in circulation. It belongs to the family Nemacheilidae, the stone and brook loaches, by far the largest family in the loach superfamily Cobitoidea and one that has absorbed many species once scattered across the old catch-all genus Nemacheilus.
Schistura is itself one of the biggest genera in freshwater fish taxonomy, with several hundred described species spread across South and Southeast Asia, and new species are still being described from single streams and river systems. The Catalog of Fishes (Eschmeyer, CAS) is the reference for the currently valid combination, and it lists this species as Schistura cataracta, Kottelat 1998, with no synonyms in wide use.
Morphology
Like other members of its genus, Schistura cataracta is a slender, cylindrical loach with a flattened belly, a pointed snout carrying barbels for probing the substrate, and paired fins set low and wide for pressing against current. FishBase records a maximum size of about 2.5 in standard length, a typical size for a small-stream Schistura. The body pattern is boldly marked: FishBase describes 8 to 12 dark vertical bars, each wider than the pale interspace between them, running along the flank above a broad dark stripe that runs the length of the body — a pattern that breaks up the fish's outline against a cobble or gravel bed.
As in other Nemacheilidae, the skin carries only minute, deeply embedded scales, leaving it effectively naked and, by extension, sensitive to harsh chemical treatment — a trait shared across the loach group generally, though it is not specifically documented for this species. Nemacheilids as a family lack the erectile suborbital spine that defines the botiid loaches; that spine is not a feature of Schistura.
Habitat
The species is known from the Nam Theun and Nam Gnouang, tributaries within the Mekong basin in Laos. FishBase describes its habitat as fast-flowing rivers over rocky and stony substrate, with the fish occasionally found over gravel or sand as well — the classic stone-loach habitat of clear, current-swept water rather than still or vegetated margins.
This is a cool-to-moderate, well-oxygenated running-water habitat, not a warm, still or blackwater one. Part of the known range now lies within the footprint of hydropower reservoirs on the Nam Theun system; the species has been recorded persisting there, but at low densities compared with the flowing-water reaches it originally occupied, underlining how tied it is to current and oxygenation rather than lake-like conditions.
Feeding
Schistura cataracta is a bottom-dwelling micro-predator in the mould typical of its genus, working the spaces between rocks and gravel for small invertebrates — insect larvae and small crustaceans are the likely staples, based on the foraging habits documented for stone loaches generally. No dedicated dietary study of this species has been located in the cache, so specifics for S. cataracta itself are not available.
In the aquarium, related Schistura species are known to take small live and frozen foods readily — Daphnia, Artemia and bloodworm are commonly cited — while often ignoring dry flake altogether. That pattern, drawn from care information for congeners such as S. hypsiura, is a reasonable guide for this species' likely needs, though it has not been verified for S. cataracta specifically.
Mating
No description of courtship or spawning behaviour for Schistura cataracta has turned up in the available sources. Data on reproduction in wild Nemacheilidae generally is thin outside of a handful of well-studied species, and this appears to be one of the many stone loaches for which the picture simply has not been documented.
Breeding
As with reproduction generally, no observations specific to Schistura cataracta are available. Going by the pattern documented across the stone and brook loaches, the species is presumed to be an egg-scatterer that releases eggs over gravel or among stones in fast-flowing water with no parental care — the standard nemacheilid strategy — but this is inference from the family, not a confirmed account for this fish. It has not been reported bred in captivity, and given how little of its basic biology has been recorded, that is unsurprising; data here is genuinely sparse rather than merely omitted.
In the aquarium
Schistura cataracta is not established in the aquarium trade, and no husbandry account for it could be found. What follows is drawn from its habitat and from care experience with related Schistura species, offered as a guide rather than a verified protocol: a tank built around this fish's needs would replicate its cool, fast, highly oxygenated stream — strong current, a rocky or gravel substrate, and clean water low in dissolved organics and nitrate, since stone loaches from swift habitats generally do poorly in stagnant or warm still water.
Being a small, naked-skinned stream fish, it would be expected to share the general loach sensitivities to copper-based and full-strength medications, though this has not been documented for the species itself. Anyone encountering it — most plausibly through specialist importers rather than general trade — should treat it as a demanding, current-loving fish rather than a beginner community species.
Conservation
The IUCN Red List assessed Schistura cataracta on 10 October 2011 and classified it as Least Concern. FishBase notes that the primary threat identified is dam construction on its home rivers — the Nam Theun hydropower development has converted stretches of its habitat from flowing river to reservoir, and the species has been recorded surviving in these impounded waters, but at low densities relative to free-flowing reaches.
Because the known range is narrow — essentially the Nam Theun and Nam Gnouang system — further hydropower development or degradation of its remaining flowing-water habitat would be the most likely route to future decline, even though the current global assessment is Least Concern. The species is not part of the aquarium trade, so collecting pressure is not a relevant factor for it.