Back gr eenish and flanks silver y. Fins hyalineto grey. Body elongate and highly compressed. Ascaleless keel extending from throat to anal fin. A decurvedand wavy lateral line. Mouth almost vertical. Pectoralfins long and curved. Lower lobe of caudal fin largerthan upper one. Lower jaw hooked in older specimensand its tubercle fits into the upper jaw notch. Gill openingsvery wide and gill membranes attached far forward,under eye level. Gill rakers reaching second or third rakerbelow when appressed. Pharyngeal teeth narrow,strongly hooked and serrated. Gut elongate and S-shape.Maximum age 9 years, total length 60 cm and weight 3.5kg. Maturity at 2-4 years and a minimum total length of12 cm. Spawning in April-May at 13.5-22°C on a sandgravelbottom. Absolute fecundity up to 100,000 eggswith an average diameter of 4.7 mm after swelling. Pelagiceggs develop in waters with a high oxygen content.Spawning may also take place in brackish water whereeggs float. Food includes zooplankton in young and insects,spiders, crustaceans, and small fish in adults.