Black Trevally, Caranx lugubris, or black jack, is a species of large ocean fish in the jack family Carangidae. The species has a circumtropical distribution, found in oceanic, offshore waters of the tropical zones of the Pacific, Atlantic and Indian Oceans. The species is particularly prevalent around offshore islands such as the Caribbean islands in the Atlantic, Hawai and French Polynesia in the Pacific and the Seychelles and Maldives in the Indian Ocean.
Black jack are rare in shallow waters, preferring deep reefs, ledges and seamounts in clear waters. The species is easily distinguished by its black to grey fins and jet black scutes, with the head having a steep profile near the snout. The largest recorded length is 1 m and weight of 17.9 kg. carango black iack
The black jack lives either individually or in small schools, and is known to school with other species. It is a predatory fish, taking a variety of fish, crustaceans and molluscs as prey. Sexual maturity is reached at 34.6 cm in females and 38.2 cm in males, with spawining taking place between February and September in the Caribbean.
The early life history of the species is very poorly understood. Black jack are of high importance to many island fisheries, but are rarely encountered in most continental fisheries. The black jack is a benthopelagi species rarely found in shallow inshore waters, preferring deep, clear offshore waters of depths from 12 to 354 m. The species is most common in insular oceanic habitats and around offshore islands, rarely found close to the continents. The black jack inhabits deep reefs and reef drop offs, also being common around oceanic seamounts. carango black iack
The black jack is of moderate to high importance to commercial fisheries throughout its range, often being the most abundant large carangid in offshore island catches. The species is taken by both various nets and traps as well as by hook and line. Black jack are usually marketed as fresh, whole fish, but they are also sold salted or dried.
The species rarity in most areas means it is not a major target for anglers, however some offshore locations such as the Bahamas the black jack is an important gamefish. The species appeal as a food fish varies between location, with some regions considering it the best table fish available. Despite this, numerous ciguatera poisoning cases have been attributed to the black jack, with laboratory tests confirming the presence of the toxin in the species flesh.
(extract from Wikipedia)