horse mackerel fish of the genus Trachurus, found in the Black Sea, the Mediterranean, and the E. Atlantic from Iceland and Norway down to S. Africa. Their maximum length is around 50 cm (20") and they have greenish-blue backs and prominent ‘stepped’ lateral lines, marked by a set of lozenge-shaped scutes (bony plates like especially large scales). In this respect they resemble many other members of the family Carangidae, to which they belong. The family, which is more important in the Indo-Pacific than in the Atlantic, is notorious for the confusion in English vernacular names (see jack); horse mackerel may also be called scad, a name more often used for carangid species in the Indo-Pacific.
