Chondrostoma nasus (Linnaeus, 1758)
Common nase
Chondrostoma nasus
photo by Muséum-Aquarium de Nancy/D. Terver

Family:  Leuciscidae (Minnows), subfamily: Leuciscinae
Max. size:  50 cm TL (male/unsexed); max.weight: 1,500.0 g; max. reported age: 15 years
Environment:  benthopelagic; freshwater, potamodromous
Distribution:  Europe: Basins of Black (Danube, Dniestr, South Bug and Dniepr drainages), southern Baltic (Nieman, Odra, Vistula) and southern North Seas (westward to Meuse). Invasive or introduced in Rhône, Loire, Hérault, Seine (France) and Soca (Italy, Slovenia) drainages. Reports from the Drin drainage including Lakes Ohrid and Skadar represent a distinct species. Asia: Turkey.
Diagnosis:  Dorsal spines (total): 3-3; Dorsal soft rays (total): 8-10; Anal spines: 3-3; Anal soft rays: 9-11; Vertebrae: 47-48. Diagnosed from congeners in Black and Caspian Sea basins by the following characters: straight mouth in individuals larger than 20 cm SL, lower lip with thick cornified sheath; dorsal fin with 9½ branched rays; anal fin with 10-11½ branched rays; scales on lateral line 52-66 (usually 60-63); eye large, diameter 50-65% of interorbital distance; and side lacking broad dark midlateral stripe. Differs from species of Chondrostoma, Protochondrostoma and Parachondrostoma in Atlantic, Adriatic and Mediterranean basins of France, Italy and Slovenia by having the following features: mouth straight, lower lip with thick cornified sheath; 27-36 gill rakers; anal fin with 10-11½ branched rays; and pectoral, pelvic, anal and caudal fins red (Ref. 59043). (Ref. 59043). Caudal fin with 19 to 21 rays (Ref. 40476).
Biology:  Gregarious. Adults occur in fairly shallow water with fast current, often beside the swirls created by piles of bridges or rocks (Ref. 30578). They inhabit moderate to fast-flowing large to medium sized rivers with rock or gravel bottom. Larvae occur below surface and feeding larvae inhabit along shores. Early juveniles live on the bottom in very shallow shoreline habitats. When growing, they move from the shore for faster-flowing waters. Juveniles overwinter in backwaters or in cavities along shores. During winter, adults form dense swarms in lower parts of rivers. Larvae and early juveniles prey on small invertebrates while larger juveniles and adults feed on benthic diatoms and detritus. Adults migrate upstream some tens of km to spawning sites which are often located in tributaries. Spawning occurs in fast flowing water on shallow gravel beds (Ref. 556, 59043). Its flesh is good but bony (Ref. 30578). Locally threatened by damming, destruction of spawning sites and pollution. In drainages where they are introduced, they outcompete and eliminate Parachondrostoma toxostoma in Rhône and Protochondrostoma genei in Soca (Ref. 59043).
IUCN Red List Status: Least Concern (LC); Date assessed: 05 March 2010 Ref. (130435)
Threat to humans:  harmless
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