Taxonomy & naming
Acantopsis multistigmatus was described by Vishwanath and Laisram in 2005 in the Journal of the Bombay Natural History Society, as part of a wider revision of the horseface loaches (genus Acantopsis) that added several new species from Southeast Asia. The type locality is the Lokchao stream, a tributary of the Yu River in the Chindwin River basin, Manipur, in northeastern India — a narrow, specific range typical of the fine-grained species splits that have come out of Acantopsis in the last two decades.
The genus sits in the family Cobitidae, the true loaches, alongside Cobitis, Sabanejewia, Lepidocephalichthys and the dojo loach Misgurnus. FishBase currently flags Acantopsis multistigmatus as likely a junior synonym of the far more widely distributed Acantopsis spectabilis, following Boyd et al. (2017); the Catalog of Fishes is the governing authority for which combination is presently valid, and this entry keeps the described name Acantopsis multistigmatus while noting that potential synonymy rather than silently merging or renaming it.
Morphology
This is a true loach in every sense: it carries the erectile suborbital spine that gives the family Cobitidae its common name, a small, sharp blade folded into a groove beneath the eye that can be flicked out defensively or when the fish is handled. Like all Acantopsis it has the elongated, pointed, downturned "horseface" snout the genus is named for, an elongated cylindrical body, and small eyes set high on the head — an adaptation for a fish that spends most of its life with its body buried in sand.
The skin carries only minute, deeply embedded scales, leaving it functionally naked and, as in other loaches, sensitive to rough substrate and to medication. Described material and closely related Acantopsis species reach roughly 4.5–6 in in length; in the absence of a species-specific maximum in the cache, this entry uses that genus-typical range rather than guessing a precise figure.
Habitat
Acantopsis multistigmatus is known from the Lokchao stream and the wider Yu River system within the Chindwin River basin of Manipur, northeastern India — a tropical Asian river system, not a temperate one. This places it squarely among the warm-water Cobitidae, in contrast to the coldwater spined loaches (Cobitis, Sabanejewia) and the dojo loach (Misgurnus) found across temperate Europe and East Asia.
Horseface loaches of this genus live over soft sand and fine sediment in flowing streams and river margins, where the substrate allows them to bury themselves for cover and to sift for food. Clean, well-oxygenated, moving water over a soft bed is the defining habitat feature of the genus, and nothing in the cached sources suggests this species departs from that pattern.
Feeding
Acantopsis is a sand-sifting benthic omnivore. In the wild it buries itself in fine sand and works mouthfuls of substrate through its gills, extracting insect larvae, small crustaceans and other invertebrates while expelling the sand — a foraging method shared across the genus and well documented for its close relatives. A soft sand substrate is not a cosmetic choice for this fish; it is how it feeds.
In the aquarium, horseface loaches take high-quality sinking foods readily: live or frozen bloodworm, Tubifex, Daphnia and brine shrimp, alongside sinking pellets or wafers. Without a fine sand bed to sift, natural foraging behaviour is lost and the fish is reduced to picking food off a substrate it cannot use the way it evolved to.
Mating
No spawning account for Acantopsis multistigmatus, or for the genus generally, is present in the cached sources, and none is offered here. What can be said follows the pattern for tropical Cobitidae: this is a scattering species with no pair-bonding or nest-building behaviour recorded, and — as with most tropical horseface and pond loaches — there is no documented courtship or sexing method established for the hobby. Any claim beyond that would be guesswork, which this entry avoids.
Breeding
As a member of the tropical branch of Cobitidae, Acantopsis multistigmatus is not known to be bred in the home aquarium. Spined and pond loaches as a family scatter adhesive eggs among plants, typically around spring conditions, and several temperate species — Cobitis, Sabanejewia, and the dojo or weather loach Misgurnus — have been spawned in ponds or unheated tanks under the right seasonal cues. The tropical Cobitidae, including the horseface loaches of Acantopsis and the genus Lepidocephalichthys, generally have not been bred by hobbyists, and this species is no exception in the available record.
Where breeding is reported at all for horseface loaches, it is described as rare and tied to specific, poorly understood environmental triggers likely linked to seasonal monsoon flooding, with commercial supply — where it exists for the genus — relying on hormone-induced spawning rather than tank breeding. There is no parental care in this group; eggs are scattered and abandoned.
In the aquarium
A fine sand substrate at least 2 in deep is essential, not optional, for this species — sharp gravel damages the sensitive snout and barbels of horseface loaches and prevents the burrowing behaviour that defines how they rest and feed. Strong filtration producing a moderate current, matching the flowing streams it comes from, suits it far better than still water. Being near-scaleless, it shares the family's sensitivity to copper-based medications and full-strength treatments, so half-doses and gentle products are the safer approach if disease treatment becomes necessary.
Size the tank to a genus-typical adult length in the low teens of centimetres, with open sandy floor space to sift and burrow rather than a densely cluttered aquascape. As with most true loaches it is best kept in a small group rather than alone, and warm tropical water parameters are appropriate given its origin in the Chindwin basin — this is not a fish for an unheated or coldwater setup.
Conservation
Acantopsis multistigmatus is assessed by the IUCN as Near Threatened, reflecting its narrow known range centred on the Lokchao stream and the wider Chindwin River basin in Manipur, India — a single-river-system endemic is inherently more exposed to habitat pressure than a widely distributed species. The cached sources do not detail the specific threats behind that assessment, so none are invented here.
FishBase's note that this name is likely a junior synonym of the more widespread Acantopsis spectabilis is itself relevant to conservation reading: if the two are eventually merged taxonomically, the combined range and status picture would differ from what a narrow-endemic reading of Acantopsis multistigmatus alone suggests. Until the Catalog of Fishes settles that question, this entry treats the name and its Near Threatened assessment as described, without assuming the merger has already happened.