Taxonomy & naming
Barbatula compressirostris was described by Nikolai Warpachowski in 1897, originally under the older, broader genus Nemacheilus, which for much of the twentieth century served as a catch-all for nearly all Eurasian stone loaches. The Catalog of Fishes — the authority for valid names — now places the species in Barbatula, part of the ongoing reshuffling of the old Nemacheilus/Noemacheilus complex into modern genera such as Barbatula, Schistura, Triplophysa and Oxynoemacheilus. Older regional literature may still list it as Nemacheilus compressirostris; that combination and the current one refer to the same fish.
The species' taxonomic standing is not fully settled. Some authors have treated Barbatula compressirostris as a junior synonym of the more widespread Barbatula toni, while others have treated it as the senior synonym of Barbatula golubtsovi — a reminder that the fine-grained taxonomy of Central Asian Barbatula is still being worked out through ongoing revision, most recently touched on in a review of Barbatula loaches from north-eastern China. This article follows the Catalog of Fishes treatment of Barbatula compressirostris as a distinct binomial.
The species belongs to the family Nemacheilidae, the stone or brook loaches, by far the largest family of loaches and one still being actively split and re-described as DNA work reaches into its many remote, poorly-collected river systems. The name Triplophysa compressirostris is treated as a synonym of this species in Eschmeyer's Catalog of Fishes.
Morphology
The specific epithet compressirostris — from the Latin compressus, "pressed together, compressed," and rostrum, "snout" — describes a laterally compressed snout, the character that distinguishes it from its closest relatives. Beyond that diagnostic feature, no detailed published description of body proportions, colour pattern or maximum size appears to exist for this species; it has not received the kind of thorough redescription that would let a keeper reliably pick it out from the handful of similar Barbatula found in the same rivers.
What can be said follows from the family. Like other Nemacheilidae, Barbatula compressirostris is a small, slender, cylindrical loach with a pair of barbels around the mouth used to feel out food on the streambed, and, typical of the family, tiny, deeply embedded scales that leave the skin close to naked — a point that matters for disease sensitivity and medication dosing rather than for appearance. Data is too sparse to give a confident maximum length here; related Barbatula species in the region run to a modest handful of centimetres, and this fish likely sits in the same range, but that should be read as an inference rather than a documented figure.
Habitat
Barbatula compressirostris is known from fast-flowing, clear streams in the Khovd River basin of northwestern Mongolia and the neighbouring Tuva Republic of Russia, with the wider ichthyofaunal record extending its range into the Ob River and Biya River systems of the Altai. These are boreal and montane drainages at real elevation, carrying cold, clear, well-oxygenated water over gravel and stone substrates rather than the warm, soft, still water associated with many lowland tropical loaches.
No species-specific temperature or chemistry data has been published for this fish. Its closest well-studied relative, the European stone loach Barbatula barbatula, tolerates a wide range from near-freezing to the low twenties Celsius and prefers distinctly cool water — around 57 °F — for spawning; given the similar montane, fast-flowing habitat of the Khovd and Altai drainages, a cool stream regime is the reasonable inference for B. compressirostris as well, and it should never be treated as a warm-water fish.
Feeding
As with the rest of the Nemacheilidae, Barbatula compressirostris is best understood as a benthic micro-predator: a fish that works the bottom of fast, clear streams picking off small aquatic invertebrates, insect larvae and crustaceans rather than grazing algae or biofilm in the manner of hillstream loaches. No feeding study specific to this species exists, but this diet pattern is consistent across its genus and family.
In practice, a fish of this kind takes readily to small live and frozen foods presented at the bottom — bloodworm, brine shrimp, small crustaceans and similar sinking fare — and may show little interest in flake left to float. Any keeper working with this species should plan around a sinking, meaty diet rather than assume it will accept generic community foods.
Mating
No sexing characters, courtship behaviour or spawning triggers have been documented for Barbatula compressirostris. Nothing in the cited literature addresses dimorphism or reproductive biology at the species level, and this article does not invent detail that has not been published.
What can be said is drawn from the wider genus and family: stone and brook loaches typically show little obvious external dimorphism outside spawning condition, and spawning in fast-flowing montane streams is generally tied to seasonal rises in flow and temperature as snowmelt and rain swell the rivers each year, rather than to any fixed calendar date.
Breeding
Stone and brook loaches of the genus Barbatula are egg-scatterers: ripe fish release eggs over gravel and among stones in fast-flowing water, with no nest-building, no cave-guarding and no parental care afterward. That is the pattern for the family generally and there is no reason to expect this species to differ, but it has not been documented spawning in the wild or in captivity, and no aquarium breeding report for Barbatula compressirostris appears to exist.
This is, honestly, one of the many Nemacheilidae species that is essentially never bred at home. A keeper should not expect to reproduce it and should treat any wild-collected or scientifically-obtained specimens as a display and research fish rather than a breeding project.
In the aquarium
Barbatula compressirostris is not an established aquarium species, and no dedicated care profile for it has been published. Any care approach has to be inferred cautiously from its genus, family and known habitat: a cold-to-cool, clear, fast-flowing, well-oxygenated stream tank with a gravel or stone substrate and strong filtration would match its known range in the Khovd, Ob and Biya river systems far better than a standard warm community setup.
As with other Nemacheilidae, the near-scaleless skin typical of the family means any specimen kept should be treated cautiously with medications — full-strength doses and copper-based treatments are best avoided or halved, and scaleless loaches are often among the first fish in a tank to show ich. Given how little is documented about this species specifically, it is best regarded as a fish for the specialist or researcher rather than a general recommendation for the hobby.
Conservation
Barbatula compressirostris has not been evaluated by the IUCN Red List and is recorded here as Not Evaluated rather than assigned a guessed status. Its range in the Khovd River basin, Tuva and parts of the Altai lies in remote, sparsely surveyed montane drainages of Central Asia, and genuine data on population trends or threats has not been published for this specific taxon.
As with many range-restricted Nemacheilidae known from a limited number of stream systems, the general pressures facing Central Asian freshwater fish — water abstraction, mining, and climate-driven changes to snowmelt and flow regimes in these headwater basins — are the plausible long-term concerns, though no assessment ties them specifically to this species. Given the taxonomic uncertainty around its status relative to B. toni and B. golubtsovi, even its distinct identity as a conservation unit is not fully settled.