It is a kind of fish. Mirror fish and flat fish are both nicknames for pomfret, and there is no difference between mirror fish and flat fish. Pomfret has a flat body, like a mirror, so it is also called mirror fish and flat fish. Pomfret is the general name for fish of the genus Pomfret in the order Perciformes, family Pomfretidae, and is also known as flat fish, mirror fish, pomfret fillet fish, and flat fish. It is a marine economic fish. Therefore, the mirror fish and the flat fish are one type of fish.