Taxonomy & naming
Carasobarbus doadrioi was formally described in 2024, with the description published in Scientific Reports (PMC11411057). The holotype measures 3 in standard length and was collected from the Khersan River at Atishgah, Karun drainage, Chaharmahal and Bakhtiari Province, Iran (31.24358°N, 50.99075°E). The species belongs to the genus Carasobarbus Karaman, 1971 — a western Palearctic assemblage of large-bodied barbs distributed across the Middle East, the Caucasus and adjacent river systems draining to the Persian Gulf and the Indian Ocean.
The old, broadly defined genus Barbus once contained most European and western Asian barbs, and many Carasobarbus species carry historical synonymies under that name or under Luciobarbus. The Catalog of Fishes (Eschmeyer, CAS) is the authority for placement, and Carasobarbus is the currently accepted genus for this group. No FishBase page for C. doadrioi had been established at the time of writing, reflecting the recency of its description.
The species epithet honours Ignacio Doadrio Villarejo, a Spanish ichthyologist with a long record of research on Iberian and Middle Eastern freshwater fishes. A diagnostic feature of juveniles under 3.5 in SL is a prominent black blotch on the caudal peduncle that fades with growth.
Morphology
The holotype of Carasobarbus doadrioi was collected at 3 in standard length, and field specimens approach 6 in SL, indicating a moderately large barb. The lateral line carries 40–44 scales — a count that figures in the original diagnosis separating it from congeners. Like other Carasobarbus, the body plan is that of a robust, fusiform river barb with the strong build and large scales characteristic of the genus.
Juveniles bear a conspicuous black blotch on the caudal peduncle; this mark fades as the fish exceeds roughly 3.5 in SL, so coloration is age-dependent. The description notes association with Luciobarbus esocinus, Garra rufa and Glyptothorax in sympatry — all species typical of large, well-oxygenated Middle Eastern rivers — lending ecological context to the morphological characters used to distinguish C. doadrioi from those co-occurring forms.
Habitat
Carasobarbus doadrioi occurs in the lower Dez River and the Karun drainage, both of which are major left-bank tributaries of the Shatt al-Arab system draining to the Persian Gulf in Khuzestan Province, Iran. Within those basins the species is most abundant in the middle and lower reaches of the Karun, where the river is wide, deep and relatively slow-moving — conditions that contrast with the fast riffles preferred by smaller benthic associates such as Garra and Glyptothorax.
Preferred microhabitats are deep sections with reduced current, abundant submerged or emergent vegetation, and rocky substrate. The Karun and Dez flow through a semi-arid to seasonally warm landscape; water temperatures and chemistry in these large alluvial rivers tend toward neutral to mildly alkaline with moderate hardness, though precise field measurements were not published in the original description. River levels fluctuate markedly with seasonal rainfall and snowmelt from the Zagros Mountains.
Feeding
No targeted feeding study has been published for Carasobarbus doadrioi at this time. By analogy with other large Carasobarbus species — and with the omnivorous feeding ecology typical of the genus — the species is expected to consume a broad diet including aquatic invertebrates, plant material, algae, and organic detritus. Large-bodied barbs in warm, productive river systems of the Middle East often feed opportunistically on benthic prey, particularly crustaceans, molluscs and insect larvae, with seasonal plant and fruit matter supplementing animal protein.
The sympatric guild of Luciobarbus esocinus, Garra rufa and Glyptothorax suggests niche partitioning: the larger, open-water Luciobarbus are piscivore-leaning, while the smaller benthic forms occupy rock surfaces and fast water. C. doadrioi's preference for deep, vegetated sections implies a diet skewed toward invertebrates and plant matter associated with that slower-flow zone.
Mating
Carasobarbus doadrioi, like all barbs, is an egg-scattering, non-guarding spawner with no nest construction and no parental care. Spawning behaviour in the genus is seasonal, typically triggered by rising water temperatures and increased river discharge associated with spring snowmelt and rainfall from the Zagros Mountains — conditions that stimulate migratory movements in many large-river barbs of the region.
Courtship follows the pattern consistent across Carasobarbus and related genera: males pursue gravid females through vegetation or over suitable substrate, pressing close as eggs and milt are released simultaneously. No pair bond is formed, no territory is defended beyond the brief act of spawning, and the fertilised eggs receive no further attention from either parent.
Breeding
As an egg-scattering barb, Carasobarbus doadrioi deposits adhesive eggs over vegetation, rocks or fine substrate in the slow, deep river sections it inhabits. Once released and fertilised, the eggs are left entirely to develop without parental guarding. Egg and larval predation by adults and other fish is the normal fate of most eggs in open-river environments, and high fecundity in large-bodied barbs compensates for that attrition.
No captive breeding of this species has been documented in the scientific or hobbyist literature — its large adult size, recency of description and restricted range in Iran mean it has not entered the ornamental trade. Seasonal temperature and hydrological cues from the Karun and Dez systems are likely the primary spawning triggers in the wild.
In the aquarium
Carasobarbus doadrioi is not established in the aquarium hobby. The species was described only in 2024 and is known from a restricted range in Iran; there are no published accounts of its export, maintenance or breeding in captivity. Its potential adult size — approaching or exceeding 6 in SL — and its origin in large, well-oxygenated Middle Eastern rivers would place it firmly in the category of a specialist fish requiring very large aquaria with strong filtration and appropriately temperate to warm water.
For hobbyists interested in congeners, other Carasobarbus species from the wider region have occasionally appeared in specialist collections, though the genus as a whole remains rare in the trade compared with the Asian and African barb groups that dominate ornamental fish sales.
Conservation
Carasobarbus doadrioi has not yet been assessed by the IUCN Red List — a consequence of its 2024 description. Its known distribution is confined to the lower Dez and Karun drainages in Khuzestan Province, southwestern Iran. Both rivers are heavily managed: the Karun is Iran's most water-rich river but also its most dammed, with multiple large hydroelectric impoundments on the main stem and tributaries altering flow regimes, blocking migratory movements, and transforming the deep, slow habitats the species depends on.
Beyond dams, the Karun basin faces agricultural water extraction, industrial pollution from refineries and petrochemical facilities in Khuzestan, and urban effluent from major cities including Ahvaz. The slow, deep vegetated microhabitat preferred by C. doadrioi is among the most vulnerable to reservoir formation and reduced downstream flow. Given the restricted range and the intensity of hydrological modification in its basin, the species warrants prompt evaluation; once assessed, a threatened category would not be surprising.