A category of fish that are characterized by their narrow bodies that are flat and oval-shaped. Similar to other varieties of fish, the flatfish begins live swimming in the same manner and position as other types of fish but as it matures, a swimming style develops that becomes horizontal rather than vertical. The eyes also begin to change as they move to one side of their head, which is the side facing upward as they swim. The distinction between the position of the eyes, either right-eyed or left-eyed enables the fish to be readily identified.
The flesh of fish is very fine grained, which allows the different types of flatfish to be interchangeable in recipes. Among the varieties of flatfish are flounder, sole, dabs, halibut, and plaices.