Taxonomy & naming
Turcinoemacheilus bahaii was formally described in 2014 by Hamid Reza Esmaeili, Golnaz Sayyadzadeh, Müfit Özulug, Matthias Geiger and Jörg Freyhof, part of a wave of Iranian nemacheilid descriptions that followed detailed morphological and genetic survey work across the country's inland basins in the early 2010s. It sits in the genus Turcinoemacheilus, a small group of stone loaches restricted to Iran, Iraq and Turkey, within the family Nemacheilidae — the stone or brook loaches, by far the largest family in the loach superfamily Cobitoidea and one that has been extensively re-split from the old catch-all genera Nemacheilus and Noemacheilus over the past few decades.
The species epithet honours Bahā' al-Dīn Muhammad ibn Ḥusayn al-'Āmilī, known as Shaykh-i Bahā'ī, a sixteenth-century Persian polymath — scholar, architect, mathematician, astronomer and poet — a naming choice that reflects the describing team's practice of honouring figures connected to Iranian scholarship and the region where the fish was collected. The Catalog of Fishes lists Turcinoemacheilus bahaii Esmaeili, Sayyadzadeh, Özulug, Geiger & Freyhof, 2014 as the currently valid name, with its type locality in the Zayandeh River basin.
Morphology
Like other members of its family, Turcinoemacheilus bahaii is a small, elongate, near-cylindrical loach adapted to holding position on the bed of a flowing stream rather than swimming in open water. FishBase records females reaching a larger size than males — up to about 3.5 in standard length, against roughly 2.5 in SL for males — with fish maturing at around 2.5 in and a recorded maximum lifespan of about five years. As in most nemacheilids, the scales are minute and the skin is effectively naked to the touch, a feature that matters for how the fish should be handled and medicated.
Detailed morphological description is confined to the technical literature, and beyond the size and growth figures captured here, published data on colour pattern, fin-ray counts and other diagnostic features for this species is sparse in the sources available. What can be said with confidence is the general nemacheilid body plan: a low-set mouth suited to bottom-feeding, paired fins used to grip the substrate in current, and an overall build that favours holding station in fast water over sustained swimming.
Habitat
This species is endemic to the Zayandeh River basin in central Iran, where it lives over gravel, pebble and boulder substrate in fast-flowing stream reaches. A dedicated growth-and-reproduction study on the population recorded water temperatures ranging from about 36 °F to 72 °F across the year, with a mean of roughly 55 °F — squarely a cool-water, not tropical, environment — and a pH between about 7.2 and 8.9 (mean close to 8.0), placing the water on the neutral-to-slightly-alkaline side rather than acidic.
The Zayandeh is a heavily used river in an arid part of Iran, and its flow regime is shaped as much by irrigation and municipal demand as by rainfall and snowmelt from the Zagros Mountains. A cool, well-oxygenated, current-swept stream bed with plenty of interstitial space among rocks is the habitat this species is built for, and it is the kind of single-basin endemic that is easy to overlook until the water it depends on changes.
Feeding
FishBase records a trophic level of about 2.8 for Turcinoemacheilus bahaii, consistent with a benthic micro-predator that forages over the streambed for small invertebrates rather than grazing algae or biofilm. This fits the general pattern for Nemacheilidae, whose members typically pick insect larvae, small crustaceans and other invertebrates from among gravel and stones in fast water.
Beyond that trophic-level figure, the cached sources do not document specific prey items or seasonal diet shifts for this species, so this profile does not go further than what is actually known: a small invertebrate-feeding micro-predator of clear, fast streams.
Mating
The growth-and-reproduction study on this population describes it as an asynchronous spawner — meaning eggs within a female mature and are released in batches rather than all at once — with a breeding season running from April to June. Recorded fecundity ranged from about 95 to 751 eggs per female, a wide spread typical of a batch-spawning stream fish where output scales strongly with body size and condition.
Spawning itself was associated with markedly cooler water than the river's summer highs, occurring at temperatures of roughly 48–53 °F — early-season conditions well below the basin's warmer months. No pairing behaviour, courtship display or nest-building has been documented for this species; as an egg-scattering nemacheilid it does not appear to form the kind of guarded spawning site seen in some other fish groups.
Breeding
Turcinoemacheilus bahaii is an egg-scatterer: ripe females release batches of eggs into the current over gravel and among rocks during the April–June season, with no nest, no guarding and no parental care of any kind afterward. This is the standard reproductive mode for Nemacheilidae generally, and there is nothing in the available sources to suggest this species departs from it.
As with the great majority of stone and brook loaches, there is no documented record of this species being bred in the home aquarium. It is not established in the ornamental trade, and what is known about its reproduction comes entirely from field study of the wild Zayandeh River population rather than from captive spawning. Data on captive husbandry and breeding is, honestly, sparse to nonexistent.
In the aquarium
Turcinoemacheilus bahaii is not a fish encountered in the aquarium trade, and no aquarium-specific husbandry information exists in the available sources. What can be inferred responsibly from its wild biology is that any attempt to keep it would need to replicate a cool, fast-flowing, well-oxygenated stream: the wild population experiences temperatures from near-freezing up to about 72 °F with a strong seasonal swing, and lives over coarse gravel and boulder substrate rather than sand or planted decor. This is emphatically not a warm, still-water community fish.
As with other nemacheilids, the near-scaleless skin typical of the family means any hypothetical captive care would call for caution with copper-based and full-strength medications. Given the complete absence of documented aquarium history, prospective keepers and researchers alike should treat this species as essentially unavailable and undomesticated rather than assume general loach-keeping guidelines transfer directly.
Conservation
Turcinoemacheilus bahaii has not been evaluated by the IUCN Red List and carries no conservation category as a result; this profile records that honestly as Not Evaluated rather than guessing at a status. As a single-basin endemic restricted to the Zayandeh River, it shares the exposure common to narrow-range Iranian freshwater fishes: the Zayandeh has been subject to severe and well-documented water-management pressure, including periods of the river running dry downstream due to irrigation diversion, damming and municipal water transfer.
No population trend, threat assessment or trade data specific to this species is available in the sources reviewed here. Its absence from the ornamental trade means aquarium collection is not a relevant pressure; the more plausible long-term risks, as for other Zayandeh basin endemics, would run through the basin's water availability and quality rather than fishing or the hobby.