The olive flounder, bastard halibut or Japanese halibut (Paralichthys olivaceus) is a temperate marine species of large-tooth flounder native to the north-western Pacific Ocean.It is often referred to as the Japanese flatfish or Korea(n) flatfish (광어) when mentioned in the context of those countries.It reaches a length of 103 cm (41 in) and a weight of 9.1 kg (20 lb).