Coffer-fish (Ostracion), a peculiar genus of bony fishes in the small order Plectognathi, and in the family Sclerodermi, which also includes the file-fishes. The body is inclosed in a firm box formed of hexagonal bony scales fitted into one another like a mosaic. The snout, the bases of the fins, and the end of the tail are the only soft-skinned parts. Over a score of species are known from tropical and subtropical seas. The best-known form is O. quadricornis from the tropical Atlantic. See GLOBE-FISH, and SUN-FISH.