Taxonomy & naming
Oxynoemacheilus parvinae was formally described in 2016 by Hamed Sayyadzadeh, Soheil Eagderi and Hamid Reza Esmaeili, from material collected in the Leilehrud stream at Sharvin village, part of the Sirvan River drainage — a Tigris tributary in Kermanshah Province, western Iran. It sits within the genus Oxynoemacheilus, a large assemblage of stone loaches distributed across the western Palaearctic — the Middle East, Anatolia, the Balkans and parts of Europe — that was carved out of the old, catch-all genus Nemacheilus (and its various synonyms) as the family Nemacheilidae was progressively revised. Within the genus, O. parvinae is placed in the O. bergianus species group, a cluster of similar, slender-bodied loaches distinguished mainly by fin-ray counts, colour pattern and details of the swim-bladder capsule.
There is no evidence in the available literature of an earlier combination for this species — it was named directly in Oxynoemacheilus rather than inherited from an older Nemacheilus or Noemacheilus assignment, so there is no defunct synonym to flag here. As with many recently described Middle Eastern nemacheilids, its exact boundaries relative to close congeners are a matter of ongoing systematic work, and the Catalog of Fishes remains the authority for tracking any future changes to its status.
Morphology
This is a small, slender loach: the type series measured roughly 1.5–3 in standard length, well within the modest size range typical of Nemacheilidae. It shows the diagnostic features used to separate it from close relatives in the O. bergianus group — 8½ to 9½ branched dorsal-fin rays, a comparatively longer head and shallower body than some congeners, an emarginate (shallowly forked) caudal fin, and large to medium dark-brown blotches scattered over the rear half of the body behind the dorsal fin. Internally, the swim-bladder capsule is angular in outline with a posterior process, a detail used by the describing authors to distinguish it from similar species.
Males possess a suborbital groove, the shallow channel beneath the eye associated with the small erectile spine found across many nemacheilid and botiid loaches alike — in this family it is far less conspicuous than the stout spine of a botiid, but the underlying groove structure is homologous. As in all loaches, the skin carries only minute, deeply embedded scales, leaving the fish effectively naked to touch and, as in every member of the group, sensitive to handling and medication.
Habitat
Oxynoemacheilus parvinae is endemic to the Sirvan River drainage, a Tigris tributary system in Kermanshah Province, western Iran; its type locality is the Leilehrud stream at Sharvin village. Like other members of the O. bergianus group, it favours fast-flowing, clear stream water running over a gravel substrate — the classic stone-loach habitat of cool, well-oxygenated riffles rather than still or sluggish water.
Detailed ecological survey data for this specific species is sparse beyond the description paper, but the pattern for its species group and drainage is consistent: clear, current-swept mountain and foothill streams feeding the wider Tigris basin. Threats noted for the Sirvan drainage in the wider literature include drought, water abstraction and pollution, all of which bear on a narrow-range stream endemic like this one even though no formal population assessment yet exists.
Feeding
No feeding study specific to Oxynoemacheilus parvinae is available, but the genus and family pattern is well established and almost certainly applies here: these are benthic micro-predators that pick small invertebrates — aquatic insect larvae, worms and small crustaceans — from the gravel and stones of fast-flowing streams. They are not grazers or detritivores in the way some hillstream loaches are; theirs is an active, opportunistic hunt along the streambed.
In the aquarium, related Oxynoemacheilus species take sinking foods readily — small live and frozen invertebrate foods (bloodworm, daphnia, brine shrimp) and sinking pellets or wafers formulated for bottom feeders — and may show little interest in flake left to float. Feeding should be aimed at the bottom, after any faster mid-water fish have had their turn, since this is a fish built to forage low in the water column.
Mating
No dimorphism or courtship behaviour has been documented for this species beyond the taxonomic note that males bear a suborbital groove associated with the small erectile spine typical of the genus — a feature used in identification rather than confirmed as a display structure. Data on sex ratios, seasonal condition changes or any external cues distinguishing mature females is not available in the sources consulted.
Across Nemacheilidae generally, stone and brook loaches are egg-scatterers that spawn opportunistically over gravel in fast-flowing water, without pairing behaviour or nest-building of the kind seen in cichlids or many catfishes. Nothing in the available literature suggests O. parvinae departs from that pattern, but in the absence of direct observation this should be read as an inference from the family, not a confirmed account for the species itself.
Breeding
As with the great majority of stone and brook loaches, Oxynoemacheilus parvinae has no documented aquarium breeding record, and no captive-spawning account appears in the sources available for this species. The expected mode, based on the family and genus, is an egg-scatterer: ripe fish release eggs over gravel and among stones in fast-flowing water, with no parental care of eggs or fry afterward — the pattern typical of Nemacheilidae generally, and quite different from the cave-guarding behaviour of gobies or the mouthbrooding seen in some cichlids.
Given how narrowly known this species is — described only in 2016 from a single Iranian drainage — it should honestly be treated as effectively unbred in captivity, with data too sparse to say more. Breeding mode: egg-scatterer over gravel in fast water; parental care: none.
In the aquarium
Oxynoemacheilus parvinae is not an established aquarium fish, and specific care guidance for it does not exist in the literature surveyed. What can be said comes from its species group and family: as a small O. bergianus-group stone loach adapted to fast, cool, clear, well-oxygenated water over gravel, it would need a tank that replicates that current and oxygenation — strong flow, a gravel or fine-gravel substrate, and clean, well-filtered water — rather than the warm, still conditions suited to many tropical community fish.
As with every loach in this atlas, its near-scaleless skin makes it sensitive to copper-based medications and full-strength treatments generally; any medication should be dosed cautiously and gently. Because it has no established trade or husbandry record, anyone encountering this species in the hobby should treat it as an uncommon, specialist fish for a dedicated cool-flow stream-biotope setup rather than a general community tankmate, and should expect very limited guidance on tank size, since no adult husbandry data has been published.
Conservation
Oxynoemacheilus parvinae has not been evaluated by the IUCN Red List; its conservation status is recorded here as Not Evaluated rather than guessed at. It is known only from the Sirvan River drainage in Kermanshah Province, western Iran, a Tigris tributary system, and appears to be a narrow-range stream endemic in the pattern typical of many recently described Middle Eastern nemacheilids.
The wider Sirvan drainage faces pressures noted in the regional literature — drought, water abstraction and pollution — any of which could affect a species restricted to a small number of streams within it, even though no formal assessment yet quantifies the risk to this particular fish. There is no evidence of an aquarium trade in this species; it is not a fish that has been commercially collected or farmed, so any conservation concern here is a habitat question for its home drainage rather than a trade-driven one.