Small fish reaching no more than 12 cm in length. It has an elongated body, of silvery coloration, with a very large head and eyes. The mouth has a prominent lower jaw.

It is a euryhaline species that can live both in the sea and in estuaries, lagoons and canal networks of coastal areas. It is mainly distributed in the Mediterranean, Black and Caspian seas, being less abundant in the Atlantic. In Catalonia it is found in the estuaries of the main rivers

They migrate between inland waters and the sea to breed, but some populations can breed in brackish water or even freshwater. It feeds on small crustaceans and other invertebrates.

It is in regression in Catalonia, due to pollution, the drying of wetlands, the pressure of exotic species and overfishing.