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The closest affinities of the rudderfishes are with the mackerel-like fishes. They have moderately stout bodies, short blunt snouts with convex profiles, and a moderately deep caudal peduncle without longitudinal keels. The single dorsal fin extends from over the pectorals to the caudal peduncle; the front part of the dorsal is spiny, either reduced to a few flexible spines covered over by the skin so that it is hard to find them, or represented by several detached spines so short that they might be overlooked, and preceding the much longer soft-rayed part of the dorsal. The tail fin is only slightly emarginate; the anal fin is similar to the dorsal in shape but much shorter; the ventrals are below the pectorals, and are smaller than the latter. The mouth is small, with small teeth in the jaws. Only two species are known off the Atlantic coast of the United States.