Taxonomy & naming
Schistura sirindhornae was formally described by Apinun Suvarnaraksha in 2015 in the journal Zootaxa, based on a holotype and paratypes collected from steep, clear, canopy-shaded streams in the upper Nan River drainage of the Chao Phraya basin, Nan Province, Thailand. It belongs to the family Nemacheilidae, the stone and brook loaches — by far the largest loach family, comprising hundreds of small, scaleless or near-scaleless species spread across cool, fast-flowing streams of Eurasia. The Catalog of Fishes lists Schistura sirindhornae as the valid combination, with no earlier synonym under Nemacheilus or Noemacheilus; unlike many of its relatives it was described directly in Schistura rather than reassigned there during the genus's many taxonomic revisions.
The species epithet honours HRH Princess Maha Chakri Sirindhorn of Thailand, recognising her long-standing support for conservation and education projects in Nan Province, where the type locality lies. As a recently described, single-locality endemic, it has not accumulated the tangled synonymy that affects older, more widely distributed Schistura; its taxonomic history begins and effectively ends with the 2015 description.
Morphology
Like other members of its genus, Schistura sirindhornae is a small, elongate, laterally compressed loach built for holding position in fast-flowing water. The original description notes overlapping scales across the entire body — a detail worth flagging, since many nemacheilids are naked or only partly scaled — along with a bright orange mark on the occiput and a distinctive crown-shaped mark between the eyes, features used to distinguish it from other Schistura in the region. Measured paratypes reached around 1.5 in standard length, with FishBase giving a maximum of about 3 in.
As in other Schistura, an erectile suborbital spine sits in a groove beneath each eye — a defensive feature shared across the stone-loach lineage, though it is far less conspicuous than the equivalent spine in the larger botiid loaches. Fine morphological detail beyond the original description — colour variation, sexual differences, growth pattern — has not been documented; this is a species known essentially from its type series.
Habitat
The species is endemic to the upper Nan River drainage, part of the upper Chao Phraya River basin in Nan Province, northern Thailand. It occupies upland streams between roughly 721 and 1,155 metres elevation — steep, clear, fast-flowing watercourses running under forest canopy, the kind of cool, well-oxygenated highland habitat typical of many Schistura across mainland Southeast Asia.
FishBase records an upper temperature limit around 64 °F and a pH up to about 6.5, consistent with a cool, soft, clear-running mountain stream rather than a warm lowland river. This is a coldwater-leaning highland fish, not a warm tropical species, and its habitat requirements sit at the opposite end of the loach spectrum from lowland, slow-water species.
Feeding
Schistura sirindhornae is recorded as a microphage feeding on aquatic insect larvae, consistent with the diet of most stone loaches: a benthic micro-predator that picks small invertebrates from the streambed and among gravel and stones in fast-flowing water.
No aquarium feeding data exists for this species specifically, since it is not established in the hobby. Based on its diet in the wild and the general pattern in Schistura, it would be expected to take small live and frozen foods such as bloodworm and daphnia readily, with flake of limited interest to a fish adapted to hunting food off the streambed.
Mating
Nothing specific to Schistura sirindhornae has been published on courtship, sexing or spawning behaviour — this is a data-sparse, recently described stream endemic, and no aquarium or field breeding observations appear in the available sources. Sexual dimorphism has not been documented for this species.
Breeding
No breeding has been recorded for this species, in the wild or in captivity, and it should not be assumed to follow any elaborate reproductive strategy. Stone and brook loaches of the genus Schistura are, as a rule, egg-scatterers that release eggs over gravel and among stones in fast-flowing water, without nest-building or parental care of any kind — a pattern quite unlike the cave-guarding of gobies or the mouthbrooding seen in some cichlids. Schistura sirindhornae is rarely if ever available in the aquarium trade, and there is no record of it having been bred in captivity; data on its reproductive biology is simply sparse.
In the aquarium
Schistura sirindhornae is not an established aquarium fish — it is a narrow-range stream endemic from a single Thai drainage, not part of the ornamental trade, and any specimens in hobbyist hands would be exceptional. Were it to be kept, its known ecology points clearly to the requirements: cool, clear, fast-flowing, highly oxygenated water reflecting its 721–1,509 ft upland stream habitat, with a temperature kept well below the range suited to typical tropical community fish (FishBase records an upper limit around 64 °F), soft acidic-to-neutral water (pH up to about 6.5), a hard substrate of gravel and stone, and strong current and surface agitation to keep oxygen levels high.
As in other Nemacheilidae, the near-scaleless or lightly-scaled skin of stone loaches makes them sensitive to copper and full-strength medications, so any treatment should be approached cautiously and at reduced dosing. Given how little is documented about this species and its total lack of aquarium history, anyone encountering it should treat it as a specialist, cool-water proposition rather than a general community fish.
Conservation
Schistura sirindhornae has not been evaluated by the IUCN Red List, so it carries no formal conservation status here — it is recorded as Not Evaluated rather than assigned a guessed category. As a species known only from the upper Nan River drainage in Nan Province, Thailand, with an elevational range of roughly 721–1,155 metres, it is by definition a narrow-range endemic, and stream endemics of this kind are typically vulnerable to habitat degradation such as deforestation, water extraction and sedimentation even without a formal assessment flagging the risk.
The species is not part of the aquarium trade, so there is no evidence of trade-driven pressure on its population; any conservation concern would stem from land use and water quality changes within its single known drainage rather than collection for the hobby.