HORSE-MACKEREL or SCAD, a genus of fishes (Caranx) found in temperate and especially in tropical seas. Some go kinds are known, the majority being wholesome food; some species at tain a length of over 3f t. The fish to which the name horse mackerel is applied in Great Britain is C. trachurus. This species is found almost everywhere within the temperate and tropical zones of both hemispheres. The horse-mackerel, together with the American horse-head or ocean old-wife (Argyeiosus vomer), the pilot-fish (q.v.), and the true mackerel (q.v.) and its allies belong to the division Scombriformes.