Caranx lugubris Poey, 1860
Jacks of the genus Caranx, often called trevallies, have prominent scutes—a line of strengthened scales that reinforce the tail. The scutes of the Black Trevally, or Black Jack, are especially easy to see. These jacks vary from almost black to dull gray, but the scutes are always dark. There is a dark spot on the upper gill cover. The species occurs singly or in pairs, typically along steep dropoffs adjacent to deep water. In Hawai`i it is known almost exclusively from the northwestern chain. The photograph above, taken at Lehua Rock off Ni`ihau, may be the southernmost recorded Hawaiian sighting. To almost 3 ft. Occurs around the world in warm seas. Photo: Lehua Rock, Ni`ihau. 80 ft.