Horse Mackerel (Carapau) So named for the legend that this fish was so such a virile swimmer that smaller fish could ride on its back like a horse, the Atlantic Horse Mackerel belongs to the jack mackerel family and is an abundant catch off the central coast of Portugal. Found in the north-eastern Atlantic, Mediterranean and Black Seas, and as far as Senegal, it is known to the Portuguese as the Carapau or chicharro- although to some know it as the scad and saurel. To the Japanese (whose local horse mackerel is Trachurus japonicus), it is known as aji, and is a popular sushi fish, admired for its pronounced flavor, abundance and low price.
Like the Atlantic Mackerel found off U.S. waters, the Horse Mackerel schools in large numbers along coastlines, feeding on squid, crustaceans and other fishes. A powerful predator and swimmer, it is a stunning fish to the eye, bearing brilliant metallic greenish-blue lines along its silvery sides. They have a large head and wide eyes, few bones to contend with but heavy bony scales along their lateral line.