gar, member of the family Lepisosteidae, freshwater fishes found in the warmer rivers and lakes of the S United States, Central America, Mexico, and the West Indies. Gars are highly predacious and destroy many useful fish. They are cylindrical fishes with long jaws and formidable teeth; their peculiar armature of diamond-shaped platelike scales, composed of a hard inorganic salt, is often found also in fossil fish. The largest species is the 9-ft (275-cm) alligator gar of the Mississippi valley. Others are the long-nosed gar ( Lepisosteus osseus ), the spotted gar, and the short-nosed gar. The name garfish is sometimes used for the gar but is more correctly applied to the saltwater gar (see needlefish). Gars are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Lepisosteiformes, family Lepisosteidae.