Taxonomy & naming
Schistura jarutanini was described by the Swiss ichthyologist Maurice Kottelat in 1990, placed from the outset in Schistura, the large genus of Old-World stone loaches that Kottelat himself has done more than anyone to define through repeated revisions of the old Nemacheilus/Noemacheilus complex. It belongs to the family Nemacheilidae, the stone and brook loaches, by far the largest of the loach families and one still being actively split and re-described species by species.
The species epithet honours Kittipong Jarutanin, the Thai ichthyologist and aquarist who collected the type specimens. The Catalog of Fishes — the authority for valid names — retains the fish in Schistura, and there is no indication in the sources consulted of a subsequent generic reassignment; keepers and researchers alike should expect to find it under this name.
Morphology
This is a small, elongated stone loach, reaching only about 2.5 in standard length (roughly 3 in total length by some accounts) — genuinely one of the smallest members of its genus. The fin formula recorded for the species is 12 dorsal soft rays and 8 anal soft rays, unremarkable for a nemacheilid.
What sets it apart is its troglomorphy: eyes that are reduced or entirely absent, an adaptation to a lifetime spent in the lightless interior of a cave stream. Unusually for a cave fish, however, it has not lost its body pigmentation — it remains well-coloured rather than the ghostly pale or pink typical of many obligate cave dwellers, which is a notable and somewhat unusual combination worth flagging rather than glossing over. Like other Schistura, it likely carries the erectile suborbital spine characteristic of the loach superfamily Cobitoidea, and, as with nemacheilids generally, its scales are small and its skin correspondingly sensitive to harsh chemical treatment — though this has not been specifically documented for the species and should be treated as a family-level inference rather than a confirmed fact.
Habitat
Schistura jarutanini is known only from Tham Ba Dan, a cave system in Lam Klong Ngu National Park, Kanchanaburi Province, in western Thailand, within the Mae Nam Kwae Yai (Kwae Yai River) basin. The type series of roughly 22 specimens was collected from the deeper sections of the cave stream, and the species appears to be a genuine cave obligate rather than an occasional visitor to subterranean water.
The water there is clear, highly oxygenated and of moderate hardness (cited up to about 12 dH), flowing over a sand substrate with abundant crevices and hiding places typical of a limestone cave stream. Temperature is recorded at 70–79 °F and pH at 6–7.5 — a cool-to-mild, well-oxygenated, flowing habitat consistent with the fast, clear streams favoured by stone loaches generally, but here entirely lightless. With records confined to a single cave system and no broader distributional data available, this species should be treated as genuinely data-sparse beyond what is summarised here.
Feeding
In the wild, Schistura jarutanini forages on benthic microorganisms, algae and detritus within its cave stream — a diet consistent with a small, bottom-dwelling micro-predator/grazer working a food-poor subterranean environment rather than the richer invertebrate hunting grounds available to surface-dwelling Schistura.
Where it has been maintained under observation, it has been reported to accept standard aquarium foods, including sinking pellets, frozen mosquito larvae, brine shrimp and daphnia, suggesting it is not an obligate specialist despite its unusual habitat. As with other bottom-oriented loaches, food should reach the substrate rather than being taken from mid-water.
Mating
No courtship or spawning behaviour has been documented for this species. Nothing in the available sources describes external sexual dimorphism, pairing, or seasonal reproductive triggers, which is unsurprising for a fish known from a single cave system and a small type series rather than sustained field study or aquarium observation.
Breeding
As with most stone and brook loaches, Schistura jarutanini would be expected to be an egg-scatterer depositing eggs over gravel or sand in flowing water with no parental care, but this is inferred from the family rather than observed directly in this species. No breeding has been reported in captivity, and data on reproduction in the wild population is likewise sparse. Given its restricted, legally protected cave habitat and its absence from the aquarium trade, captive breeding attempts are essentially unknown, and none should be expected or encouraged.
In the aquarium
Schistura jarutanini is not a practical or appropriate aquarium fish. It is protected under Thai law within its national-park cave system, collection from its only known habitat is illegal, and its extremely restricted, highly specific subterranean environment — cool, dark, fast-flowing, highly oxygenated cave-stream water — is very difficult to replicate convincingly in a home tank. It is documented here for scientific and educational interest, not as a stocking recommendation.
Where the species has nonetheless been kept for observation, sources describe a need for a well-filtered tank with strong oxygenation, a sand substrate, and abundant hiding places, at a temperature of 70–79 °F and pH 6–7.5 — cooler and more current-dependent than most tropical community setups, in keeping with its stone-loach ancestry. As with nemacheilids generally, its small scales likely make it sensitive to harsh medication, though this point has not been specifically confirmed for the species.
Conservation
Schistura jarutanini is assessed by the IUCN as Vulnerable, an assessment dated 2011. This reflects its occurrence at a single known locality — the Tham Ba Dan cave system — with a small recorded population (the type series numbered only around 22 specimens), the classic profile of a range-restricted cave endemic vulnerable to any disturbance of its one known site.
The species is protected by Thai law, and removal from its habitat is illegal; it is not, and should not be, part of the aquarium trade. Because it is known from a single cave system within a national park, its conservation is bound tightly to the protection of that specific site — groundwater quality, cave access and disturbance, and the integrity of the Lam Klong Ngu National Park karst system — rather than to any broader river-basin pressures.