Around 540 flatfish species belong to the taxonomic order Pleuronectiformes, meaning “sideswimmer.” Flatfish are found throughout the world, though the most commercially important family, Plueronectidae, is concentrated in northern waters. Yellowtail is the most important Atlantic Coast flounder, and petrale sole is the most important West Coast species. Flatfish have both eyes on one side of the head, though they begin life as normal fish. As they become bottom dwellers, one eye migrates to the other side, resulting in “right-eyed” and “left-eyed” flatfish. Soles and flounders harvested commercially in North America are right-eyed, except fluke. Flounder fillets vary in shape, depending on the species. Gray sole offers long, slender fillets; yellowtail flounder, rock sole, lemon sole, fluke and dab offer thicker, broader fillets.