Mesogobius batrachocephalus, the knout goby or toad goby, is one of the species of gobiid fish native to the Black Sea and the Sea of Azov basins. It lives in estuaries and brackish water lagoons, occasionally in fresh waters also. It prefers areas near cliffs with sandy, shelly or rocky substrates at depths of from 20 to 60 metres (66 to 197 ft), sometimes down to 100 metres (330 ft). The knout goby is a piscivore. It can reach a length of 34.5 centimetres (13.6 in) SL and weight of 600 grams (1.3 lb). Maximum known age is eight years.