Flounders are flatfish that live in ocean waters in Northern European waters and along the east coast of the United States and Canada, as well as the western Pacific. The name "flounder" refers to several geographically and taxonomically distinct species. In Europe, the name flounder refers to Platichthys flesus, in the Western Atlantic there are summer flounder Paralichthys dentatus, southern flounder Paralichthys lethostigma, winter flounder Pseudopleuronectes americanus among other species, and in Japan the Japanese flounder Paralichthys olivaceus is common.
After metamorphosis, flounder lie on one side on the ocean floor; either the left or right side might face upward depending on the species. During metamorphosis one eye migrates to the other side of the body so that both eyes are situated on the upward-facing side of its body. Flounder sizes typically vary from five to fifteen inches, though they sometimes grow as large as three feet in length. Their breadth is about one-half of their length. Flounder are ambush predators and their feeding ground is the soft mud of the sea bottom, near bridge piles, docks, and other bottom incumbrances; they are sometimes found on bass grounds as well. Their diet consists mainly of fish spawn, crustaceans, polychaetes and small fish.
