Chondrostoma, Agassiz, 1835

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 331-333

Chondrostoma

A genus of middle-sized to large Leuciscids, found from France to the Volga, and Iran. Together with the Anatolian Turcichondrostoma , they are related to the west European genera Achondrostoma , Iberochondrostoma , Pseudochondrostoma , Parachondrostoma , and Protochondrostoma , which all form one monophyletic lineage. All nases are also related to the European Leuciscid genera Phoxinellus and Telestes and the West Asian genus Pseudophoxinus , although the precise phylogenetic relationships between these groups remain unclear.

In West Asia, 11 out of 12 species of Chondrostoma are characterised by a well-developed rostral cap covering most of the upper lip and a variably developed cornified cutting edge on the lower jaw. Chondrostoma are slender

fishes that inhabit fast-flowing waters near or on stone bottom. They obtain their food by scraping algae growing on stones and rocks and invertebrates living among them, which we refer to as “aufwuchs” (literally, ‘growth’). Adults have an inferior mouth with a cornified sheath covering the lower lip, often with a sharp edge. In some species, the mouth is arched, as in most leuciscids. In more specialised species, the anterior edge of the lower lip (bearing the cornified sheath) is straight. In such species, the lower lip is distinctly fleshy only at the corners of the mouth, and the cornified sheath appears as a blade. The mouth morphology changes during ontogeny and all species with a straight mouth in adults have an arched mouth when they are juveniles. In West Asia, all Chondrostoma are difficult to distinguish, and many species are very closely related. The published diagnoses of several species do not provide an effective means of differentiating them. Consequently, the following keys are presented as a provisional guide only. Given their close phylogenetic relationship, future studies are anticipated to reveal some of the species to be conspecific.

Further reading. Elvira 1987 (revision); Robalo et al. 2007 (phylogeny); Geiger et al. 2014 (phylogeny); Çiftçi et al. 2020 (phylogeny).

Chondrostoma beysehirense ; Lake Beyşehir basin, Türkiye; 140 mm SL.