Fusiform body, more slender than that of bluefin or bigeye. Small eyes and head. Longer 2nd dorsal and anal fins than any other tuna (which get longer with age). The liver is without striations on the ventral surface, and a swimbladder is present. There are 26-35 gill rakers on the first gill arch. The pectoral fins usually reach beyond the origin of the 2nd dorsal fin but not beyond the end of its base. Yellowfin have a dark blue back with a yellow lateral band on the upper sides. The lower sides and belly are silvery-gray, often with chains of white vertical lines and spots. The 2nd dorsal and anal fins are yellow, and the finlets are yellow with a narrow black margin. Common size: 16 to 67 inches.