Taxonomy & naming
Oxynoemacheilus tongiorgii was described by Nalbant and Bianco in 1998, placed in the genus Oxynoemacheilus, one of several genera carved out of the old catch-all Noemacheilus/Nemacheilus as the stone-loach family Nemacheilidae was progressively split up through molecular and morphological revision. The Catalog of Fishes, the standing authority for valid fish names, retains it in Oxynoemacheilus, and that is the combination used here.
The species epithet honours Paolo Tongiorgi (1936–2018), an Italian marine biologist. Beyond the original description and a handful of karyological surveys of the Kor River basin's endemic loach fauna, very little taxonomic literature exists on this species — it is one of many Nemacheilidae known chiefly from a type description and a scatter of follow-up notes rather than a body of research.
Morphology
Like other members of its family, Oxynoemacheilus tongiorgii is a small, elongate, cylindrical loach built for holding position on the bed of a running stream rather than for open swimming. FishBase records a maximum size of about 3 in total length, placing it among the smaller stone loaches. Detailed morphological description beyond the original taxonomic paper is sparse, and no aquarium-photography record or hobbyist account could be found to confirm colour pattern in life.
A karyotype study has been carried out on the species, finding a diploid chromosome number of 2n = 50 (18 metacentric + 24 submetacentric + 8 subtelocentric chromosomes, NF = 92) — useful for confirming its distinctness from related Kor River basin loaches, though it says nothing about external appearance. As in its Nemacheilidae relatives, the skin is essentially scaleless or very finely scaled, a trait that matters far more for aquarium husbandry than for field identification; whether this particular species carries the erectile suborbital spine seen in some nemacheilids is not confirmed in available sources, so it is not asserted here.
Habitat
This is a genuine single-drainage endemic. Oxynoemacheilus tongiorgii is known only from the Kul River basin, part of the wider Kor River drainage in Fars Province, southern Iran — a subtropical freshwater system fed by springs rather than by a large perennial river. The type locality was a spring near the town of Darab; that spring has since dried up, and the species' modern stronghold is the Ghadamgah spring-stream system within the same basin.
Spring-fed stream habitat of this kind is typically cool, clear and well-oxygenated, running over gravel, sand and rock rather than through still or vegetated water — consistent with the demersal, bottom-hugging habits FishBase records for the species. Because the type locality has already vanished and the entire known population depends on a small number of spring outflows, this is a fish whose entire habitat could plausibly be described on a single map with room to spare.
Feeding
FishBase describes Oxynoemacheilus tongiorgii as omnivorous/detritivorous, consistent with the general pattern in small Nemacheilidae: picking small invertebrates, insect larvae and organic detritus from the streambed rather than actively hunting in open water. No dedicated dietary study of this species could be found, so this should be read as a general characterisation rather than a species-specific breakdown of stomach contents.
In practical terms, a fish with this feeding style would be expected to take small live and frozen foods readily and forage over sinking foods on the bottom, in keeping with its relatives across the family — but this is inference from the broader group rather than a documented account of this species in captivity, since none appears to exist.
Mating
No courtship or spawning behaviour has been documented for Oxynoemacheilus tongiorgii; FishBase explicitly notes breeding data as unknown, and no other source in hand adds to that. This is typical for a narrow-range spring endemic that has drawn taxonomic and karyological attention but essentially no life-history study.
What can be said follows from its family: Nemacheilidae are egg-scattering fish with no pair-bonding or nest-building behaviour recorded across the group, so any reproduction in the wild is presumed to follow that general pattern rather than anything resembling the cave-guarding or mouthbrooding strategies seen in unrelated fish groups. That inference is offered cautiously, in the absence of any direct observation of this species.
Breeding
There is no record of Oxynoemacheilus tongiorgii being bred, or even kept, in the aquarium hobby. Consistent with stone and brook loaches generally, the expected mode is an egg-scatterer depositing eggs over gravel or among stones in flowing water, with no parental care — but this is a family-level inference, not an observation specific to this species, and it should be read as such.
Given the species' extremely restricted range, its dependence on a shrinking set of spring habitats, and the complete absence of any aquarium-trade or captive-breeding history, the honest statement is simply that this is a data-sparse species that has, as far as available sources show, never been spawned in captivity.
In the aquarium
Oxynoemacheilus tongiorgii does not appear to be present in the aquarium trade in any documented way — no hobbyist care profile, retailer listing or forum account could be found. It should not be treated as an available or recommended aquarium fish; this entry exists to document a genuine, poorly known wild species rather than to promote it as a tank candidate.
Were a keeper ever to encounter this species, the general husbandry expectations for small Nemacheilidae would apply: cool, clean, well-oxygenated, flowing water over a gravel or sand substrate, small live or sinking foods, and — because loaches as a family tend to be scaleless or near-scaleless and unusually sensitive to copper and full-strength medications — cautious, reduced-dose treatment of any disease. None of this has been verified for this species specifically, and given its Data Deficient status and single-drainage range, it is not a fish that should be collected or traded casually.
Conservation
The IUCN Red List now assesses Oxynoemacheilus tongiorgii as Critically Endangered. It is recorded as a rare species known from a single location within the Kul River basin, part of the Kor River drainage in Fars Province, Iran.
The loss of the original type locality — a spring near Darab that has since dried up — is a concrete and troubling data point underscoring that vulnerability. A species restricted to one basin's spring-fed streams is inherently vulnerable to groundwater extraction, drought and habitat alteration, and the fact that its only known population today lives in a different spring system (Ghadamgah) from the one it was described in underscores how narrow its margin for survival may be. No aquarium trade pressure is documented for this species; any threats are habitat-driven.