The flounder has a roughly oval shape, with both eyes on the right side of its head and has a small mouth and pointed snout. The lateral line curves slightly around the pectoral fin. It has a smooth body except for some rough scales along the lateral line and a row of prickly humps along the base of the dorsal and anal fins. The caudal peduncle is long, accounting for about half the length of the tail. The topside colour is variable from dull brown to greyish-green, often with small orange spots, while the underside is white. The flounder grows up to 50 cm in length.Identification of Plactichthys flesus
is made more difficult by the existence of 'reversed individuals' in which the eyes are on the left side of the body. Hybrid individuals have been know to occur through interbreeding between flounder and plaice (Pleuronectes platessa
) (Dipper, 2001).