Taxonomy & naming
Schistura doonensis was described by Tilak and Husain in 1977 from the Dehra Dun (Doon) valley of Uttar Pradesh, India — the locality that gives the species its epithet. It was placed, as most South and Southeast Asian stone loaches of the era were, in the old, broadly defined genus Nemacheilus, a catch-all that has since been extensively split.
Subsequent revisions of the Nemacheilidae have moved a large share of the species once lumped in Nemacheilus into other genera, chiefly Schistura, and some sources list the current combination for this fish as Schistura doonensis. The Catalog of Fishes is the authority for the valid name; this article follows the original combination, Schistura doonensis, as used in the cataloged record consulted for it. Whichever generic name is current, the species and its type locality are the same fish, and a reader encountering either name in older or newer literature should treat them as referring to one animal.
This fish was long listed as Nemacheilus doonensis; Eschmeyer's Catalog of Fishes places the species in Schistura, and the current combination Schistura doonensis is followed here.
Morphology
Schistura doonensis belongs to the Nemacheilidae, the stone or brook loaches — the largest family of loaches, made up mostly of small, slender, benthic fish adapted to clear, fast-flowing water. Like its relatives it is expected to have an elongate, sub-cylindrical body, a flattened belly suited to holding position on the streambed, and the erectile suborbital spine typical of many loaches in this broader group, along with the near-scaleless or fine-scaled skin that makes loaches generally sensitive to medication.
No detailed published description of colour pattern, fin counts or precise body proportions for this species was found in the sources consulted. This is common among Nemacheilidae, many of which are known only from their original description and a handful of museum specimens; rather than guess at colour or pattern, it is more honest to note that the data here are sparse and that anyone wanting a certain identification should refer to the original 1977 description.
Habitat
The species is recorded from clear, swift streams with pebbly beds in the Dehra Dun area of Uttar Pradesh, in the foothills below the Himalaya in northern India. This kind of water — cool to moderately warm, fast-flowing, well-oxygenated and running over stone and gravel rather than soft substrate — is the typical habitat for Nemacheilidae across South and Southeast Asia, and it fits the general pattern for stone and brook loaches from the Himalayan foothill zone.
No information on seasonal water-level change, associated species or fine-scale habitat structure was found for this species specifically. Given the limited number of records, it should be treated as a narrow-range stream fish of the Doon valley rather than one with a broad, well-documented distribution.
Feeding
As a member of the Nemacheilidae, Schistura doonensis can be expected to be a benthic micro-predator in the manner typical of the family: picking small invertebrates, aquatic insect larvae and other tiny prey from among stones and gravel in fast-flowing water, rather than grazing algae or taking food from the water column.
No diet study specific to this species was located in the sources reviewed. The feeding note above reflects the general pattern for fast-water stone loaches of its family and region rather than a direct observation of this fish.
Mating
No information on sexual dimorphism, courtship or spawning behaviour specific to Schistura doonensis was found. Stone and brook loaches as a family are not well studied in this respect even for common aquarium species, and for a narrow-range species like this one, known mainly from its original description, no such data appear to exist in the literature consulted.
What can be said, by analogy with better-known Nemacheilidae, is that stone loaches typically show little obvious external difference between the sexes and reproduce by scattering eggs in fast water rather than through any elaborate courtship display or pair formation.
Breeding
Stone and brook loaches of the family Nemacheilidae are, as a rule, egg-scatterers: ripe adults release eggs over gravel or among stones in flowing water, with no nest-building, no cave-guarding by a male, and no parental care of eggs or fry afterward. There is nothing in the sources reviewed to suggest Schistura doonensis departs from that general family pattern.
No record of this species being spawned in captivity was found, and given how little aquarium presence it has, that is unsurprising. As with most Nemacheilidae outside a small handful of well-known genera, it should be assumed rarely or never bred in the home aquarium; anyone encountering breeding claims for this species specifically should treat them with caution absent a documented source.
In the aquarium
Schistura doonensis has essentially no presence in the aquarium hobby — no dedicated care profile was found on the hobbyist sites consulted, and it does not appear to be an established trade species. Anyone who does encounter it, whether through specialist importers or local collection near its Indian range, should treat the general Nemacheilidae care pattern as the starting point: cool-to-moderate, clean, fast-flowing, well-oxygenated water over a gravel or stone substrate, since that is what fast-water stone loaches are built for, rather than the warm, still conditions suited to lowland community fish.
As with loaches generally, the near-scaleless skin typical of the family means caution with copper-based and full-strength medications is warranted, and any group-living tendencies should be assumed rather than assumed absent until better information exists. Given the lack of documented husbandry, this is a fish best regarded as unavailable to the hobby rather than as a species with an established care routine.
Conservation
Schistura doonensis is listed as Data Deficient on the IUCN Red List (2022 assessment), meaning there is not enough information on its population, range or trends to assign a threat category. This is a common outcome for narrow-range stream loaches known from a limited area and a small number of historical records.
The species is known from the Dehra Dun valley of Uttar Pradesh, India, an area that has seen substantial urban and agricultural development pressure on its streams over recent decades. No specific population assessment or threat data beyond the Data Deficient listing were found in the sources reviewed, so no further claim about its conservation status can be made honestly; it is presented here as an example of the many Nemacheilidae whose status is genuinely unknown rather than confirmed safe.