Description: The body of the jack mackerel is rather elongate; somewhat compressed. The body tapers to a tail, which is as broad as it is deep. The color is metallic blue to olive green above becoming silvery below. The jack mackerel, which is not a true mackerel, is quite similar to the Mexican scad, but can be distinguished by the enlarged scales along the side and by the last rays of the dorsal and anal fins being attached to the body. These rays are isolated finlets on the Mexican scad.