Round goby includes mollusks, crustaceans, worms, fish eggs, zebra mussels, small fish, and insect larvae. Adult round gobies feed mainly on mollusks and other small invertebrates (insects and amphipods) living on the bottom of lakes and streams. At spring, the main items in its diet in the Sasyk Lagoon are "Hydrobia", "Cerastoderma", "Abra". In the same season near the Romanian coasts of the Black Sea the round goby feeds on polychaetes, crustaceans ("Idotea balthica", "Pachygrapsus marmoratus", "Xantho poressa", etc.) and juvenile gobies. Near Sevastopol the round goby feeds on molluscs ("Mytilaster lineatus", "Abra" spp.), but near Karadag except molluscs ("Cerastoderma", "Brachiodontes") were
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