The European flounder (Platichthys flesus) is a flatfish of European coastal waters from the White Sea in the north to the Mediterranean and the Black Sea in the south. It has been introduced into the United States and Canada accidentally through transport in ballast water. It is caught and used for human consumption.

The European flounder is oval in shape and is usually right-eyed. It normally grows about 30 cm in length, although lengths of up to 60 cm have been recorded. The upper surface is usually dull brown or olive in color with reddish spots and brown blotches and this fish can change color to suit its background, providing an effective camouflage. The underside is pearly-white, giving the fish one of its common names, the white fluke. The lateral line features rows of small tubercles, as do the bases of the dorsal and anal fins.

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