Distinguished from congeners in Europe by the following combination of characters: 1-2 enlarged canine teeth in anterior part of each jaw; second dorsal fin with 18-22½ branched rays; and 80-97 scales on lateral line (Ref. 59043). Description: Long slender body, without cross-bars. No spines on the gill cover (Ref. 35388). Caudal fin with 17 soft rays (Ref. 40476).
Habitat: Large, turbid rivers and eutrophic lakes; brackish coastal lakes and estuaries.
Biology: Lives up to 17 years. Spawns for the first time at 3-10 years, usually at four. Spawns in April-May, exceptional from late February until July, depending on latitude and altitude, when temperatures reach 10-14C in spawning grounds (lowest temperature for egg incubation 11.5C). May undertake short spawning migrations. Individuals foraging in brackish water migrate to freshwater habitats (migrations of up to 250 km have been recorded). Homing well developed, even nearby populations may be relatively isolated. Males are territorial and excavate shallow depressions about 50 cm in diameter and 5-10 cm deep in sand or gravel, or among exposed plant roots on which eggs are deposited, usually in turbid water and at 1-3 m depth. Spawns in pairs, at dawn or night. Female remains over the nest while male circles rapidly around, at about 1 metre from nest. Then male takes a vertical orientation and both swim around swiftly, and eggs and sperm are released. After all the eggs are released female leaves the nest site. Male defends the nest and fans the eggs with his pectorals. Females spawn once a year. Feeding larvae are positively phototactic and feed on pelagic organisms after they leave the nest for open water. Piscivorous, feeding mostly on gregarious, pelagic fishes.