Body deep quadrangular shaped and compressed. Small head with steep dorsal profile, slightly concave above the eye. Small terminal mouth with very small teeth arranged in plates forming brush-like surface. Gill membrane united at isthmus. Dorsal fin with deep notch between spinous and soft ray portion. Membrane between dorsal and anal fins strongly incisions. Caudal fin round in juveniles, truncated to double emarginated in adults. Very small ctenoid scales cover the body, head and extend to dorsal and anal fins base.
color : body silvery-grey to silvery-green or yellow with large, well separated, black or dark brown spots. Juveniles (up to 4 cm SL) are more colorful with red-orange dorsal surface with bars and dark dots.
size : common 3-20 cm (max. 30 cm).
The body shape and the color pattern of this species differ significantly from all other Mediterranean species.
BIOLOGY / ECOLOGY
Very euryhaline species. Feeds on benthic invertebrates, algae and detritus. Reaches sexual maturity at 14 cm (females) or 12 cm (males). Reproduction occurs in marine environment but the juveniles and subadults inhabit freshwater, estuaries and mangrove swamps.
habitat : mainly protected coastal marine environments, estuaries and freshwater source.