Rhodeus colchicus

Common name. Georgian bitterling.

Diagnosis. Distinguished from other species of Rhodeus in West Asia by: ● second infraorbital bone wide / ● 33−36, usually 34−35,total vertebrae / ● 30−38,usually 33−35,scales in lateral series. Size up to 81 mm SL.

Distribution . Caucasian Black Sea basin of Russia from Kherota south to Natanebi in Georgia.

Habitat. Slow-flowing streams and small rivers, backwaters, ponds, and lakes, usually with dense underwater vegetation and sand-silt substrate.

Biology. Spawns April–September. Mating and spawning behaviour similar to R. amarus . Larvae incubated by Unio bivalves. Feeds on algae, benthic insect larvae, and planktonic crustaceans.

Conservation status. LC; frequent and widespread within its small range.

Further reading. Elanidze 1983 (morphology, biology); Bogutskaya & Komlev 2001 (description); Bohlen et al. 2006 (phylogeography); Bartáková et al. 2019 (phylogeny).