The flathead flounder, Hippoglossoides dubius, is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on bottoms in shallow coastal waters, at depths of between 10 and 600 metres (33 and 1,969 ft). Its native habitat is the northwestern Pacific, particularly the seas of Japan and Okhotsk, and the coastlines of Kamchatka and Korea. It grows up to 45 centimetres (18 in) in length.