Leucaspius delineatus Common name. Sun bleak. Diagnosis. Distinguished from other Leuciscidae in Black and Marmara Sea basin by: ○ lateral line incomplete with about 8–12 pored scales / ○ keel covered by scales between pelvic origin and anus / ○ mouth superior / ○ 11–13½ branched anal rays. Size up to 90 mm SL. Distribution. Türkiye: Izmit west to Susurluk drainage in Marmara basin, including Lakes Apolyont and Manyas (L. thracicus). Azov and Black Sea basin south to Rioni drainage (L. owsianka), northern and western Caspian basin (south to Sefid drainage in Iran) (L. dimorphus). In Europe, from lower Rhine and northern Germany east to Pechora drainage; Black Sea basin south to Rioni drainage, northern and western Caspian basin; Aegean Sea basin (from Maritsa to Nestos). Absent in Italy, Adriatic basin, Great Britain, and Scandinavia (except southernmost Sweden). Widely introduced in France, upper Rhine drainage, and locally in Great Britain and Switzerland. Habitat. Lowland riverine habitats, especially oxbows and other water bodies connected to rivers only during floods. Often found in ponds, steppe lakes, and small bodies of water not connected to rivers. May occur in any habitat with few or no predators. Biology. Gregarious. Spawns first time with one year; only for a single season. Spawns May–September when temperatures reach 16–18°C. Females may spawn about once every 3 weeks. Males are territorial; they clean spawning area and guard eggs, tied in strings around roots, reeds, aquatic vegetation, or any material floating on water surface. Feeds mainly on zooplankton and terrestrial insects. Stunted populations can form in predator-free habitats. Often rapidly invades newly created water bodies by as yet-unknown mechanisms.In Europe, scales were used to produce Essence d’Orient to coat artificial pearls. Conservation status. LC. Further reading. Arnold & Längert 1995 (biology); Kottelat & Freyhof 2007 (distribution, biology, diagnosis); Özuluğ & Saç 2019 (distribution).

Published as part of Freyhof, Jörg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, GmbH, Berlin / Boston :De Gruyter on page 347, DOI: 10.1515/9783111677811, http://zenodo.org/record/17881367