Taxonomy & naming
Paraschistura susiani was formally described in 2015 by Jörg Freyhof, Golnaz Sayyadzadeh, Hamid Reza Esmaeili and Matthias Geiger, in a review of the genus Paraschistura from Iran that introduced six new species at once, published in Ichthyological Exploration of Freshwaters. It is placed in the family Nemacheilidae, the stone or brook loaches, the largest and most species-rich family within the true loaches (Cobitoidea) and a group whose taxonomy has been repeatedly reshuffled as older catch-all genera such as Nemacheilus and Noemacheilus have been split into narrower, better-defined genera including Paraschistura, Schistura, Triplophysa and Barbatula.
The Catalog of Fishes (Eschmeyer, CAS), the authority for valid names, lists the species as Paraschistura susiani, with the type material collected from the Jarahi drainage in the Tigris River basin. As with several of its Iranian congeners, the species is known essentially only from its original description; no subsequent taxonomic revision or additional field study appears to have added materially to what is known of it.
Morphology
Paraschistura susiani is a small fish, reaching only about 1.5 in in standard length, in keeping with the modest size typical of Nemacheilidae. Like other members of the family it has an elongate, cylindrical body built for hugging the substrate in current, a flattened underside, and a small, downturned mouth surrounded by barbels for probing the streambed. As in other loaches, an erectile spine sits in a groove below the eye — the suborbital spine characteristic of the true loaches — though it is far smaller and less conspicuous than the heavier spines of the botiid loaches.
The original description distinguishes Paraschistura susiani from its close relatives chiefly by scalation and by a secondary sexual feature: the species has scales covering the back and flanks (rather than a naked or partly-naked body, as seen in some congeners), and males develop an oval, blunt suborbital flap. Beyond these diagnostic details, published morphological data for the species are sparse — typical of a narrow-range stream endemic described only recently.
Habitat
The species is known from the Jarahi drainage — the Marun, Ab-e Ala and Zard Rivers — in Khuzestan Province, southwestern Iran, part of the wider Tigris River basin at the base of the lower Zagros Mountains. It occupies the demersal, bottom-dwelling zone of these rivers, recorded across a range of stream habitats including runs, riffles and pools, all built on rocky substrates with clear, flowing water.
Specific temperature and pH readings for the type locality have not been published, so precise water-chemistry figures are not available. Given the subtropical climate of the lower Zagros foothills and the fast, riffle-and-run habitat the species occupies, it is reasonable to expect cool-to-moderate, well-oxygenated flowing water typical of Zagros piedmont streams, but this should be read as an inference rather than a measured fact — the honest position is that detailed habitat data for this species are sparse.
Feeding
No dedicated dietary study of Paraschistura susiani has been published. FishBase records a trophic level of about 2.8 for the species, consistent with a mild omnivore leaning toward small invertebrate prey rather than a strict carnivore or herbivore — a pattern shared broadly across Nemacheilidae, whose members typically pick insect larvae, small crustaceans and other invertebrates off rocky and sandy streambeds.
In the absence of species-specific data, the safest inference is that Paraschistura susiani forages as a bottom micro-predator, in the manner of its genus and family, taking benthic invertebrates from among stones and gravel in fast water. This has not been confirmed by direct observation or gut-content analysis, and should be treated as an inference from its relatives rather than a documented fact.
Mating
Nothing has been published on the reproductive behaviour, courtship or sexual maturation of Paraschistura susiani. The only sexual character noted in the original description is morphological rather than behavioural: males possess an oval, blunt flap beneath the eye that females lack, a common style of secondary sexual signal in this genus, though its function in courtship has not been studied in this species.
As with most narrow-range Nemacheilidae, there is no record of this species having been observed spawning in the wild or reproducing in captivity. Its reproductive biology should be considered entirely unknown pending future fieldwork or aquarium observation.
Breeding
Paraschistura susiani has never been bred in the aquarium, and no scientific account of its spawning behaviour exists. Based on the well-documented pattern across Nemacheilidae, stone and brook loaches of this kind are egg-scatterers: ripe adults release eggs over gravel and among stones in flowing water, with no nest-building, guarding or other parental care afterward. There is no cave-spawning male-guarder behaviour and no mouthbrooding in this family — those breeding modes belong to entirely different fish groups.
This species is not present in the aquarium trade and its breeding biology is, honestly, a complete blank in the literature. That is the correct and expected state for a narrow-range stream endemic described only in 2015 from a handful of Iranian drainages, and it should not be filled in with speculation.
In the aquarium
Paraschistura susiani is not a hobby fish. It is not known to be traded, kept, or bred in aquaria anywhere, and there is no husbandry record to draw on. Any care guidance here would necessarily be invented rather than sourced, so none is offered — this is a research-only species at present.
What can be said, by extension from its family, is that stone and brook loaches of this kind are near-scaleless-skinned bottom dwellers of cool, fast, highly oxygenated water, traits that make Nemacheilidae generally sensitive to poor water quality, copper-based medications and stagnant conditions. Anyone encountering this species outside its native range — for instance via scientific collection — should assume it needs clean, well-aerated, flowing water rather than a warm, still community tank, but this is a general family-level expectation, not species-specific data.
Conservation
Paraschistura susiani has not been assessed on the IUCN Red List and is classified here as Not Evaluated. No numeric population data, threat assessment or trend information has been published for the species.
As a narrow-range endemic restricted to a handful of rivers in a single Iranian drainage, it is the kind of species that would typically warrant an IUCN assessment once resources allow; until then, Not Evaluated is the honest and correct classification rather than an assumed status of Least Concern or Data Deficient. It is not known to be affected by the aquarium trade, which does not deal in this species.