Petroleuciscus borysthenicus (Kessler, 1859)

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 354-355

Petroleuciscus borysthenicus

Common name. Bobyretz.

Diagnosis. Distinguished from other species of Petroleuciscus in West Asia by: ○ 8–9½ branched dorsal rays / ○ 9–10½ branched anal rays / ● iris orange to red / ● 7 scales between lateral line and dorsal origin / ○ 33–40 total lateral line scales / ○ posterior margin of anal convex or almost straight / ○ no black pigments along free margin of each flank scale. Size up to 185 mm SL.

Distribution. Marmara basin east to Lake Sapanca, but absent from Anatolian coast east of Sakarya, except for two records from Samsun. Caucasian Black Sea basin of Russia and Georgia. Lower parts of all tributaries of northern Black Sea and Azov basins except Don. Aegean basin from Struma drainage ( Greece) eastwards.

Habitat. Lowland streams, rivers, lower reaches of mountain rivers, lakes, deltas, and backwaters with moderate to no current. Prefers warm water up to 30–32°C. Tolerant of low oxygen concentrations, sometimes found in marshes and waters with dense vegetation. Tolerant of slightly brackish water. Prefers sand, sand-mud, or mud bottoms. Prefers shallow areas with slow currents along banks, backwaters, small lakes, and similar still waters.

Biology. Lives up to 8 years. Spawns first time at 2–3 years, males may spawn in first year. Forms spawning aggregations of up to 150 individuals. Spawns April–June at 12–28°C in 0.1–1.0 m deep water over sandy or slightly muddy bottom. Females lay 2–3 portions of adhesive eggs on or

Petroleuciscus ninae ; Büyük Menderes, Türkiye; ~ 60 mm SL.

among aquatic plants. Usually found in groups of 5–30 individuals close to bottom, but sometimes close to surface, under floating leaves or other objects. Does not migrate but moves to deeper water in winter. Feeds mainly on insects, their larvae, plankton, benthic invertebrates, and algae.

Conservation status. LC; extirpated from Lake İznik basin. Further reading. Movchan & Smirnov 1981 (description, biology); Kottelat & Freyhof 2007 (biology, distribution); Saygun et al. 2017 (distribution); Özpiçak et al. 2022 (distribution).