Taxonomy & naming
Schistura rebuw was formally described in 2019 by Choudhury, Dey, Bharali, Sarma and Vishwanath in the journal Zootaxa, based on specimens from the Pachai stream, a tributary of the Kameng River near Seppa in East Kameng District, Arunachal Pradesh, India. It sits in the genus Schistura, by far the largest genus in the family Nemacheilidae with well over 230 described species spread across South and Southeast Asia — a genus that has absorbed many species once placed in the old catch-all Nemacheilus or Noemacheilus as the family has been repeatedly revised.
As a species described this recently, S. rebuw has not been the subject of any taxonomic revision since its description, and the Catalog of Fishes — the standing authority for valid fish names — recognises it in Schistura. There is no synonymy to untangle here; the combination Schistura rebuw is the only one the species has ever carried.
Morphology
Like other members of its genus, Schistura rebuw is a small, elongate, near-scaleless loach built for holding station on the bottom of fast water, with an erectile suborbital spine tucked beneath the eye — a defensive structure shared across the Cobitoidea. The original description records a greyish-beige body crossed by 10–11 blackish bars, a fairly typical Schistura banding pattern that helps break up its outline against a stony streambed.
The species is best known for an unusual and diagnostic form of sexual dimorphism in the suborbital region: females possess a slit in the tissue below the eye, while males instead have a flap — a distinction sharp enough that it likely contributed to the fish being recognised as a new species in the first place. Detailed measurements, fin-ray and scale counts beyond the type description, and maximum size are not reported in the sources available here; as with many recently described micro-endemic Schistura, this is a case where the honest answer is that fuller morphological data has not yet been compiled outside the primary literature.
Habitat
The species is known from the Pachai stream, a tributary of the Kameng River system near Seppa, East Kameng District, in the Indian state of Arunachal Pradesh — foothill terrain on the southern flank of the eastern Himalaya. Streams of this kind are typically clear, cool-to-cool-temperate, fast-flowing and well-oxygenated, running over mixed gravel, small stones and sand, which matches the general habitat pattern documented for other Schistura in the region.
No dedicated water-chemistry survey of the type locality is reported in the sources reviewed here, so specific temperature, pH and flow figures for this exact stream are not given; the values below are drawn from the general habitat requirements of related Schistura species in similar Himalayan-foothill streams, not from a site-specific reading, and should be treated as a reasonable proxy rather than measured data for S. rebuw itself.
Feeding
No feeding study specific to Schistura rebuw is available. Across the genus, Schistura are bottom-dwelling micro-predators that forage over stony and gravelly substrate for small aquatic invertebrates — insect larvae, worms and small crustaceans — picked from between and beneath stones in the current, a pattern well documented in related species such as S. hypsiura.
There is no reason from the available description to expect S. rebuw to differ from this genus-wide pattern, but in the absence of direct observation of this species' wild diet, that inference should be read as extrapolation from its relatives rather than a confirmed fact about S. rebuw.
Mating
The species' most notable biological feature is directly relevant here: the sexes are distinguished by different soft tissue below the eye, a slit in females and a flap in males, rather than by the size or colour differences more commonly used to sex loaches. Beyond this diagnostic character, nothing has been published on courtship, spawning triggers, or seasonal migration for Schistura rebuw specifically.
Other stone and brook loaches in the family typically spawn as rains raise stream flow, scattering eggs rather than pairing up or building any structure, and there is no evidence pointing to different behaviour here — but this is inference from the family, not an observation of this species.
Breeding
No captive or field spawning record exists for Schistura rebuw; this is an essentially unstudied, freshly described stream endemic with no aquarium history. Based on the well-documented pattern across Nemacheilidae, stone and brook loaches are egg-scatterers that release eggs over gravel and among stones in fast-flowing water, with no nest-building, mouthbrooding, or parental care of any kind afterward.
That genus-wide pattern is the honest expectation for this species too, but it has not been confirmed by anyone breeding or observing S. rebuw in spawning condition. Data here is genuinely sparse, and the species has no place in the aquarium trade or hobby breeding record to draw on.
In the aquarium
Schistura rebuw is not established in the aquarium hobby; it has no trade history, no common name in circulation, and no keeper reports to draw on. Anything said here has to be extrapolated cautiously from its genus, and should be read that way rather than as species-specific guidance.
Related Schistura, such as S. hypsiura, are kept as cool-to-mild, fast-flowing-stream fish over coarse sand, gravel and rounded stone, in clear, well-oxygenated, low-nitrate water with strong circulation — closer to a hillstream setup than a typical still community tank. Like other nemacheilids it is likely near-scaleless and therefore probably sensitive to copper-based medications and full-strength treatments, a caution that applies broadly across the loach group. Until the species is actually available and observed in captivity, any tank recommendation for S. rebuw specifically would be guesswork, and none is offered here beyond that general genus-level caution.
Conservation
Schistura rebuw has not been assessed on the IUCN Red List, so it is recorded here as Not Evaluated rather than assigned a guessed category. As a species known only from a single hill stream system in Arunachal Pradesh, described as recently as 2019, it is exactly the kind of narrow-range endemic that tends to remain unassessed for years after description simply because formal review has not caught up.
A review of endemicity and conservation status among Arunachal Pradesh's recently described fish species has flagged S. rebuw as locally significant precisely because of that narrow range, though it stops short of proposing a formal status, noting that population size, trend and habitat condition data are all lacking. There is no evidence of aquarium-trade collection pressure on this species; any conservation concern here would be about habitat in its home stream system, not the ornamental trade.