Taxonomy & naming
Schistura notasileum was described in 2016 by Endruweit, Yang & Liu in Zootaxa (4168(3):594–600), based on a holotype (catalogued KIZ 2016000361, 2 in standard length) collected from the main channel of the upper Mekong River at Dali Prefecture, Yunnan, China. As with most recent Schistura descriptions, the species was distinguished from its congeners on details of colour pattern, fin-ray counts and body proportions rather than any single obvious external trait.
Schistura is the largest genus in Nemacheilidae, the stone and brook loaches, and one of the most actively revised groups in Cobitoidea — older literature often used the broader genera Nemacheilus or Noemacheilus for fish now placed in Schistura, Triplophysa or Barbatula. The Catalog of Fishes is the authority for the current combination, and it stands as Schistura notasileum; this profile keeps that genus rather than any older synonym.
Morphology
The type specimen measured 2 in standard length, placing S. notasileum in the small-to-modest size range typical of Schistura, most of which run from roughly 1–4.5 in SL depending on species. As a nemacheilid it shares the family's general build: an elongate, cylindrical body, a flattened head and underslung mouth suited to picking food off the streambed, and — where present in the genus, as in most Schistura — an erectile suborbital spine, a small defensive spine hidden in a groove below the eye that can be flicked out when the fish is handled.
Like other stone and brook loaches, the skin is effectively naked or covered only in minute embedded scales, a trait that matters for husbandry as much as anatomy. Detailed morphometrics, fin-ray formulae and colour-pattern specifics beyond the original description have not been compiled here; this is a recently described species with a thin published record, and it is honest to say so rather than invent detail.
Habitat
The type locality is the main channel of the upper Mekong River near Dali, Yunnan, China — fast-flowing, clear water at what appears to be an unusually cool temperature for a tropical Schistura, recorded around 52 °F, with a slightly alkaline pH near 8.3 and moderate conductivity (roughly 510 µS/cm). This combination of cold, swift, highly oxygenated water is consistent with a headwater or high-elevation river reach rather than a warm lowland stream, and the species marks the northernmost known distribution boundary for the genus Schistura along the Mekong.
As a nemacheilid stone loach, S. notasileum fits the family's general habitat profile: clear, fast, cool-to-cool-temperate flowing water over stone, gravel and sand, with strong dissolved oxygen. This is not a still-water or blackwater species, and nothing in the available record suggests warm, sluggish habitat.
Feeding
No dietary data specific to S. notasileum has been published. Stone and brook loaches as a group are bottom-foraging micro-predators, sifting sand and gravel in fast water for small invertebrates — aquatic insect larvae, worms and small crustaceans — and this is the reasonable expectation for this species as well, pending direct observation.
In the aquarium, related Schistura and other nemacheilids are fed small live and frozen foods such as daphnia, brine shrimp and bloodworm, along with sinking foods that reach the bottom; they generally show little interest in flake left to float. No aquarium feeding record exists for S. notasileum itself, so this should be treated as a genus-level expectation rather than a documented fact for the species.
Mating
Nothing has been published on the reproductive behaviour, sexual dimorphism or spawning biology of Schistura notasileum specifically. This is a recently described species known essentially from its type series, and no courtship or pairing observations — wild or captive — appear in the available literature.
For context, stone and brook loaches as a family are not known for elaborate pairing behaviour: related Schistura and other nemacheilids typically pair or group loosely around spawning rather than forming lasting bonds, with little to no reliable external sexing beyond body plumpness in ripe females. None of that has been confirmed for this species, and it should not be assumed to apply without direct evidence.
Breeding
There is no record of Schistura notasileum being bred in captivity, and this is unsurprising: it is a recently described, narrow-range river species with essentially no aquarium history. What is known of stone and brook loach reproduction in general — and this is a family-level pattern, not a claim about this species — is that they are egg-scatterers over gravel and stone in fast-flowing water, with no parental care, and that captive breeding across Nemacheilidae is rare.
Breeding.mode for this profile is set accordingly: egg-scattering over gravel with no parental care, following the honest pattern for the group, and data on this specific species remains sparse to nonexistent. Anyone encountering this fish in the trade should not expect a bred or even a well-documented wild-collected fish; it is effectively unknown outside its type description.
In the aquarium
Schistura notasileum has no established aquarium history, and it is not known to be traded. If it were kept, the collection data point strongly toward a cool-water setup rather than a standard tropical community tank: fast flow, high dissolved oxygen, and water on the cool side of what most tropical fishkeepers run, echoing the roughly 52 °F recorded at its type locality — though a captive-care temperature range has not been established and should not be assumed to match that extreme wild reading exactly.
As with other nemacheilids, the near-scaleless skin typical of the family means any stone loach should be treated cautiously with medications — copper-based treatments and full-strength doses are best avoided or halved. A sand-and-gravel substrate, smooth stones, and strong water movement mimicking a stream reach would be the reasonable starting point for this or any closely related Schistura, but this is a general nemacheilid-care inference, not a documented care record for this species.
Conservation
Schistura notasileum has not been evaluated by the IUCN Red List. Given its very recent description (2016) and narrow, specific type locality on the upper Mekong main channel near Dali, it is likely a poorly known, possibly range-restricted species, but no formal assessment or population data exists to characterise its conservation status one way or another.
The Mekong basin as a whole faces well-documented pressures from damming, water-flow alteration and development, and headwater reaches like the one that yielded this species are not exempt from those pressures. Without a published assessment, though, this profile records the status honestly as Not Evaluated rather than inferring a threat level from general basin trends.