any of the half dozen species of fishes in the family Monodactylidae (order Perciformes), found from the Atlantic coast of western Africa to the Indo-Pacific region and usually inhabiting inshore or estuarine waters. They are extremely compressed and deep-bodied and are often greater in height than in length. Because of this shape and the characteristic silvery colour, they are sometimes called moonfishes.

The moonfish, or mono (species Monodactylus argenteus), a popular aquarium fingerfish found from eastern Africa to Malaysia, attains lengths of 20 cm (8 inches) and has two black bands extending vertically down its head. The striped fingerfish (M. sebae), of western Africa, is also a popular aquarium fish.