Taxonomy & naming
Schistura tenura was formally described by the Swiss ichthyologist Maurice Kottelat in 2000, placed from the outset in the genus Schistura within the family Nemacheilidae — the stone and brook loaches, the largest of the loach families and one that has absorbed many species once scattered across the old, now largely defunct genera Nemacheilus and Noemacheilus. No evidence points to this species ever having been placed in those older genera; it was named directly as Schistura tenura and the Catalog of Fishes, the standing authority for valid fish names, has not moved it since.
The species epithet tenura draws on Latin tenuis, "thin" or "slender," combined with Greek oura, "tail" — a name that points straight at the fish's slim, elongate build. Nemacheilidae itself is a genus-rich, frequently revised family, and Schistura is one of its largest genera, with hundreds of species distributed across mainland and insular Southeast Asia; S. tenura is a single, narrowly distributed member of that much larger group.
Morphology
This is a small fish even by stone-loach standards, reported at a maximum of about 2 in standard length. Like other Schistura it has the classic nemacheilid build: an elongate, sub-cylindrical body, a flattened belly suited to gripping stone in current, and a slender caudal region reflected in its own name. As in the wider genus, an erectile suborbital spine is expected beneath the eye — a defensive structure typical of the group — though the type material has not been described to this atlas in enough anatomical detail to confirm its exact form in this species; readers should treat that as inferred from the genus rather than confirmed for S. tenura specifically.
Detailed morphometric and colour-pattern data for this species are not available from the sources consulted for this profile. What is documented is scale reduction typical of Nemacheilidae generally — small, embedded scales over a mostly smooth-feeling body — which, combined with its size, marks it as an unremarkable-looking but highly specialised inhabitant of clear, stony streams rather than a showy display fish.
Habitat
Schistura tenura is known only from the Nam Leuk basin, a tributary of the Nam Mang in Laos — a single river system in the Mekong drainage of Southeast Asia. It was recorded in a small stream running over a rock-and-stone bed, the classic microhabitat of a stone loach: fast, clear, well-oxygenated water tumbling over a coarse substrate rather than the slow, silty or vegetated margins favoured by many other freshwater fish.
No temperature, pH or other water-chemistry data for the type locality were found in the sources reviewed for this profile, so specific figures are not given here rather than guessed. Given the genus and the stream habitat described, cool-to-moderate, fast-flowing, highly oxygenated water is the reasonable expectation, consistent with other Nemacheilidae from similar hill-stream settings in mainland Southeast Asia — but this should be read as an inference from habitat type, not a measured record.
Feeding
FishBase records a trophic level of roughly 3.0 for Schistura tenura, consistent with an omnivorous-to-detritivorous diet typical of small benthic stream loaches — grazing algae and biofilm off stones alongside small invertebrates and organic detritus picked from the streambed. No detailed dietary study specific to this species was found.
This places it firmly in the same feeding guild as most of its stone-loach relatives: a bottom-oriented micro-forager rather than an active predator of larger prey, working the same rock-and-stone substrate it is recorded from. Because the species is not in the aquarium trade, there is no husbandry-derived feeding information to add.
Mating
No information on sexual dimorphism, courtship or spawning behaviour for Schistura tenura was found in the sources consulted for this profile. This is not unusual for a narrow-range stream loach that has not been recorded since 1998 and has never been the subject of captive study or aquarium observation.
What can reasonably be said follows from the genus: Nemacheilidae as a family are egg-scatterers rather than nest-builders or mouthbrooders, with no known parental care, and spawning tied to conditions in fast-flowing stream habitat. Whether S. tenura specifically breeds seasonally, migrates within its home stream to spawn, or shows any dimorphism between the sexes is simply not documented, and this profile does not guess at specifics the record does not support.
Breeding
There is no record of Schistura tenura being bred, or even held, in the aquarium hobby. It has never entered the ornamental trade, and as a species not seen in the wild since 1998, there is no realistic prospect of captive-breeding data emerging soon.
By analogy with other stone and brook loaches in the genus, the expected pattern would be an egg-scatterer depositing eggs over gravel or among stones in flowing water, with no parental care — the standard Nemacheilidae mode. But this is inference from the family, not an observation of this species, and it should be read that way: data on breeding in S. tenura is, honestly, sparse to non-existent.
In the aquarium
Schistura tenura is not and has never been an aquarium fish. It is unknown in the ornamental trade, has no established husbandry record, and — given it has not been recorded in the wild since 1998 despite its status as Critically Endangered — is not a species anyone should expect to encounter for sale. There is nothing here to responsibly recommend in terms of tank size, water parameters or tankmates, because none of that has ever been tested with this species.
If it were ever rediscovered, the general expectations for a small Nemacheilidae stone loach would apply — cool-to-moderate, fast-flowing, well-oxygenated water over a rocky substrate, and the near-scaleless skin common to the family that makes such loaches sensitive to copper and full-strength medications. But for now this entry exists to document the species' status, not to offer care advice for a fish that is not, and should not be, in the trade.
Conservation
Schistura tenura is listed as Critically Endangered on the IUCN Red List, assessed in January 2011. The assessment notes that the species has not been recorded since 1998 and that no recent searches have been conducted to confirm its continued existence — a status that sits at the sharpest edge of data uncertainty for a freshwater fish: not confirmed extinct, but with no evidence of persistence either.
Its entire known range is the Nam Leuk basin, a tributary of the Nam Mang in Laos, making it, by definition, an extreme single-locality endemic. Small stream systems like this across Laos face pressure from damming, land-use change and sedimentation, any of which could plausibly have already affected this species' only known habitat. Until a targeted survey of the Nam Leuk is carried out, the honest status of Schistura tenura is unresolved rather than settled — a species the record has essentially lost track of.