Taxonomy & naming
Paracobitis atrakensis was formally described in 2014 by Hamid Reza Esmaeili, Hamed Mousavi-Sabet, Golnaz Sayyadzadeh, Mansour Vatandoust and Jörg Freyhof, who separated it from its congeners on the strength of caudal-fin shape and scale pattern. The species name refers directly to the Atrak (Atrek) River, the type locality and the basin to which it is essentially confined.
It sits in the genus Paracobitis, part of the family Nemacheilidae — the stone or brook loaches, by far the largest and least-known family in the loach superfamily Cobitoidea. Nemacheilid taxonomy in the Middle East and Central Asia has been repeatedly revised as researchers split old catch-all genera like Nemacheilus and Noemacheilus into narrower, better-defined groups; Paracobitis is one of the genera that resulted, and the Catalog of Fishes currently recognises P. atrakensis as a valid, distinct species within it.
Morphology
This is a small, elongate stone loach reaching a maximum reported length of about 5 in, with most individuals seen closer to 2 in. Like other Nemacheilidae it lacks true body scales over most of its length — the skin is essentially naked, with only a few scattered scales noted along the dorsal adipose crest in some individuals — and it carries the small, erectile suborbital spine typical of the group, though it is far less conspicuous than the prominent spine of a botiid loach.
The most useful identifying feature separating P. atrakensis from other Middle Eastern Paracobitis species is its caudal fin, described as truncate to only slightly emarginate rather than deeply forked. Beyond this diagnostic detail and its general body plan, published morphological description is limited, and no verified photographs or additional anatomical notes beyond the original paper and FishBase's summary were found in this research pass.
Habitat
Paracobitis atrakensis is endemic to the Atrek (Atrak) and Bidvaz River drainages of Razavi Khorasan Province in northeastern Iran, close to the Caspian Sea basin and the Turkmenistan border. As with most Nemacheilidae, it is a fish of fast, clear, well-oxygenated streams running over gravel and stone substrate — the archetypal stone-loach microhabitat, where the flattened, bottom-hugging body shape lets it hold position against current.
FishBase classifies it as a freshwater, demersal, subtropical species, consistent with the mountain and foothill stream systems of this part of Iran. No published water-chemistry data — temperature range, pH, or seasonal variation — were located for this specific species; given the genus and region it likely experiences a temperate-to-subtropical seasonal swing rather than constant warm water, but this is inference from habitat type rather than a measured record, and it is presented here as such.
Feeding
No diet study specific to Paracobitis atrakensis was found. Based on its body plan and the well-documented feeding ecology of Nemacheilidae generally, it is reasonable to describe it as a bottom-foraging micro-predator, picking small aquatic insect larvae, crustaceans and other invertebrates from among the gravel and stones of its home streams.
There is no hobby literature describing captive feeding for this species, since it does not appear to be established in the aquarium trade. Any care should follow the conservative default for small stone loaches: sinking foods able to reach the substrate, with an expectation that the fish would take live or frozen invertebrate foods more readily than dry flake.
Mating
No courtship or mating behaviour has been documented for this species. Sexual dimorphism is not described in the sources located for this profile, and given how recently the species was described and how narrow its known range is, this is unsurprising — field studies of a single-basin endemic rarely extend to behavioural observation.
What can be said is inferred from the wider Nemacheilidae: stone and brook loaches typically pair or aggregate loosely to spawn over open gravel in flowing water, without courtship displays or nest-building. Whether that generalisation holds for P. atrakensis specifically has not been confirmed.
Breeding
Breeding has not been documented for Paracobitis atrakensis, in the wild or in captivity. The genus and family strongly suggest the typical Nemacheilidae pattern: an egg-scatterer that releases adhesive or semi-adhesive eggs over gravel and among stones in fast-flowing water, with no parental care of eggs or fry afterward.
There are no aquarium hobby reports of this species being kept, let alone spawned, and stone and brook loaches as a group are rarely bred in captivity even where they are available in the trade. For this narrow Iranian endemic the honest summary is that breeding is undocumented and, on present evidence, has likely never been achieved or attempted outside its native streams.
In the aquarium
Paracobitis atrakensis is not established in the aquarium hobby; no keeper reports, care sheets, or trade listings were found during this research pass. It should not be assumed available, and any specimen offered under this name should be treated with caution given how easily small Middle Eastern nemacheilids are mislabelled.
Were it to be kept, the sensible approach would follow the general rule for stone and brook loaches: cool-to-moderate, clear, fast-flowing, highly oxygenated water over a gravel or stone substrate, with strong filtration to replicate current. As a near-scaleless loach it should be assumed sensitive to copper-based medications and full-strength treatments, in line with the rest of the family, and any medicating should be conservative and closely monitored. Given the small maximum size of around 5 in, a modestly sized stream-style tank with good flow would be the starting point, but this is a projection from family-level care norms rather than a tested recommendation for this specific species.
Conservation
Paracobitis atrakensis has not been evaluated by the IUCN Red List; it carries no formal conservation status, recorded here honestly as Not Evaluated rather than guessed. It is listed as an Iranian endemic in national freshwater fish checklists, underscoring its restricted range within the Atrek and Bidvaz drainages.
As with many single-basin endemics in this region, the fish's conservation relevance lies in the vulnerability that narrow range implies: any water extraction, damming, pollution or habitat alteration within the Atrek or Bidvaz systems could disproportionately affect its entire population, even without a formal assessment yet confirming decline. There is no evidence of aquarium-trade collecting pressure on this species.