Black bluish to deep purple or black on the head, with white belly, scaleless area with 15+ broad, nearly vertical dark bars. Pectoral and pelvic fins purple with black inner sides. Robust, elongated, rounded body; small conical teeth in a single row. Short pectoral fins not reaching vertical line from scaleless area. Large single interpelvic flap. Body naked except for a well-developed corselet (over 6 scales wide under second dorsal). Strong central keel on each side of caudal base with two smaller keels.

It looks like Auxis thazard (Frigate mackerel), both species share a robust, elongated, and rounded body shape, short pectoral fins, and a well-developed corselet. However, Auxis rochei has a narrower posterior end of the corselet (1-5 scales wide under the second dorsal fin origin) compared to Auxis thazard (10-15 scales wide).