Black goby live among stones and bladder wracks, lurking for prey. Leaning on the bottom, with their characteristically united abdominal fins, black goby observe their surroundings with big bulging eyes seeking their prey, such as worms, mollusc and crustaceans. They inhabit bottoms alone or in pairs. Females attach their eggs onto water plants or stones, while male guards them until the young hatch. Although they are only about 10 centimetres long, black gobies are the largest gobies in Finland. In the Baltic region, they have spread to the Åland archipelago, Åland and the shores of the Bothnian Sea.