The mushroom goby (Ponticola eurycephalus) is a species of goby native to the Black Sea where it can be found along the coasts from Bulgaria to the Crimea. Mostly a species of marine and brackish waters, it is known to enter fresh waters in the delta of the Danube River. This species prefers inshore waters with rocks or fallen trees. This species can reach a length of 20 centimetres (7.9 in) TL.