The name "flounder" is used for several only distantly related species, though all are in the suborder Pleuronectoidei (families Achiropsettidae, Bothidae, Pleuronectidae, Paralichthyidae, and Samaridae). Some of the better known species that are important in fisheries are:
In its life cycle, an adult flounder has two eyes on one side of its head, and at hatching one eye is on each side of its head. One eye migrates to the other side of the body through a metamorphosis as it grows from larval to juvenile stage. As an adult, a flounder changes its habits and camouflages itself by lying on the bottom of the ocean floor as protection against predators. As a result, the eyes are then on the side which faces up. The side to which the eyes migrate is dependent on the species type.
Flounders ambush their prey, feeding at soft muddy areas of the sea bottom, near bridge piles, docks and coral reefs.
A flounder's diet consists mainly of fish spawn, crustaceans, polychaetes and small fish. Flounder typically grow to a length of 22-60 centimeters (8.7-23.6 in), and as large as 95 centimeters (37 in). Their width is about half their length. Male Platichthys are known to display a pioneering spirit, and have been found up to 80 miles off the coast of northern Sardinia, sometimes with heavy encrustations of various species of barnacle.
Fluke, a type of flounder, are being farm raised in open water by Mariculture Technologies in Greenport, New York.
World stocks of large predatory fish and large ground fish, including sole and flounder, were estimated in 2003 to be only about 10% of pre-industrial levels, largely due to overfishing. Most overfishing is due to the extensive activities of the fishing industry. Current estimates suggest that approximately 30 million flounder (excluding sole) are alive in the world today. In the Gulf of Mexico, along the coast of Texas, research indicates the flounder population could be as low as 15 million due to heavy overfishing and industrial pollution.