The Isthmus goby (Arcygobius baliurus) is a species of goby native to marine and brackish waters of the Indian Ocean and the western Pacific Ocean where it can be found at depths of from 3 to 15 metres (9.8 to 49.2 ft). This species lives on substrates consisting of a mix of sand and rubble. This species grows to a length of 10.2 centimetres (4.0 in) SL. This species is the only known member of its genus.[2]