Greater amberjacks, Seriola dumerili, are the largest of the jacks. They usually have dark stripes extending from nose to in front of their dorsal fins. They have no scutes and soft dorsal bases less than twice the length of the anal fin bases. They are usually 18 kg (40 pounds) or less, and are found associated with rocky reefs, debris, and wrecks, typically in 20 to 75 m (10 to 40 fathoms).
Lesser amberjacks, Seriola fasciata, have a proportionately larger eye and deeper body than the greater amberjack. They are olive green or brownish-black with silver sides and usually have a dark band extending upward from their eyes. Juveniles have split or wavy bars on their sides. The adults are usually under 5 kg (10 lbs). They are found deeper than other jacks, commonly 50 to 130 m (30 to 70 fathoms).
Amberjacks are voracious predators, which feed on squid, fish, and crustaceans, and are thought to spawn offshore throughout most of the year.Juveniles can be caught in about 25 feet (7.6 m) of water, near floating objects.