Body r elatively compr essed and deep. Scalesrelatively small. Mouth nearly horizontal to oblique,equal jaws or lower jaw slightly behind upper one.Fleshy keel between base of pelvic fins and vent. Lastunbranched dorsal fin ray thickened, spine-like andsmooth. Anterior pharyngeal tooth compressed andbluntly pointed, remainder beveled with a cutting edgeand a hooked tip. Gut elongate and S-shape with a largeanterior loop in larger fish. Peritoneum silvery with varyingconcentrations of pigments, or black. Favors sidebranches off large rivers. Maximum total length 21 cm.Females grew faster and larger than males. Maturity in 1-2 years. Sex ratio 1male:1.8females. Spawning in Marchto late August. Absolute fecundity up to 11,000 eggs of1.2 mm in diameter. Food include crustaceans, insects,plant, gastropods, detritus and phytoplankton.