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, such as the coastal Lake Siutghiol in Romania. It prefers areas near cliffs with sandy, shelly or rocky substrates at depths of from 20mto60mm (70feetto200feetm), sometimes down to 100m (300feet). The knout goby is a piscivore. It can reach a length of 34.5cm (13.6inches) SL and weight of 600g. Maximum known age is eight years.