The flathead grey mullet (Mugil cephalus) is an important food fish species in the mullet family Mugilidae. It is found in coastal tropical and subtropical waters worldwide. Its length is typically 30 to 75 centimetres (12 to 30 in). It is known with numerous English names, including the flathead mullet, striped mullet (US, American Fisheries Society name), black mullet, bully mullet, common mullet, grey mullet, sea mullet and mullet, among others. The flathead grey mullet is a mainly diurnal coastal species that often enters estuaries and rivers. It usually schools over sand or mud bottoms, feeding on zooplankton. The adult fish normally feed on algae in fresh water. The species is euryhaline, meaning that the fish can acclimate to different levels of salinity.