moonfish

noun, plural (especially collectively) moon·fish, (especially referring to two or more kinds or species) moon·fish·es.

1. Also called horsefish, horsehead. any of several silvery marine fishes of the genus Selene, having a very compressed body and inhabiting shallow coastal waters.
2. the opah.
3. any of various other rounded, silvery fishes.

noun plural -fishes or -fish

1. any of several deep-bodied silvery carangid fishes, occurring in warm and tropical American coastal waters
2. any of various other round silvery fishes, such as the Indo-Pacific Monodactylus argenteus
3. another name for opah