Round goby the "enemy release hypothesis". Round goby The round goby ("Neogobius melanostomus") is a euryhaline bottom-dwelling goby of the family Gobiidae, native to central Eurasia including the Black Sea and the Caspian Sea. Round gobies have established large non-native populations in the Baltic Sea, several major Eurasian rivers, and the North American Great Lakes. Round gobies are small, soft-bodied fish, characterized by a distinctive black spot on the first dorsal fin. Their eyes are large and protrude slightly from the top of the head and, like most gobies, round gobies have pelvic fins that are fused to form a single disc
Sand goby rounded. In males, there is a conspicuous dark spot on the anterior dorsal fin and in both sexes there is a black patch on the caudal peduncle. The general colour is sandy brown with indistinct dark blotches and reticulations on the dorsal surface and dark striations on the pale fins. The colour of the male darkens during the breeding season and his fins become more coloured. The average size is about . The sand goby normally lives at greater depths than the common goby. It feeds on small invertebrates living on the seabed especially amphipods. It is well camouflaged and