moonfish

Moonfish is a common name applied to several different fish species rather than a single scientific group. The two most frequently referred to are the opah, genus Lampris, and the silver moony, Monodactylus argenteus. The name “moonfish” likely derives from the rounded, moon-like shape of these fishes.

Opah, or opahs, are large, laterally compressed, disk-shaped pelagic fish found in temperate and tropical oceans worldwide. They are notable for being endothermic, able to warm parts of their body above surrounding water temperatures. This adaptation helps them hunt in cooler, deeper waters. Opah have broad pectoral fins and a striking silvery body with contrasting fins. They are targeted by commercial fisheries in several regions and are sold fresh fillet a in various markets. Size varies by species, with some individuals reaching substantial lengths.

Silver moony, or moonfish in aquarium and some regional contexts, refers to Monodactylus argenteus. This species is smaller, typically inhabiting warm, brackish coastal waters and estuaries of the Indian Ocean and western Pacific. It has a tall, laterally compressed body and feeds on a variety of small invertebrates and crustaceans. In addition to its presence in the wild, the silver moony is popular in the aquarium trade in some areas and is occasionally marketed for culinary use where available.

The term moonfish can be ambiguous, and regional usage sometimes refers to other similar-looking fish. When identifying moonfish, it is helpful to check the scientific name to avoid confusion.