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A flatfish is a member of the order (Pleuronectiformes) of ray-finned demersal fishes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development. Some species face their left side upward, some face their right side upward, and others face either side upward...