Scad, better known in the kitchen as horse mackerel, is the small, oily, richly savoury flesh of several slender jacks of the genus Trachurus — most often the Atlantic horse mackerel (Trachurus trachurus) of the eastern Atlantic and Mediterranean. A schooling open-water fish with a hard, sawtooth keel of bony scutes running down its silver flank, it is one of the world's great everyday food fishes: grilled and salt-dried across the Philippines as galunggong, filleted and cured as one of Japan's most beloved aji, and fried, marinated and canned around the Mediterranean.