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Giant Trevally
Caranx ignobilis
Coastal reefs, lagoons, drop-offs and atoll channels; also open ocean.
Large, deep-bodied silver jack with a steep head profile. Older individuals become darker, almost black.
Identification
Giant trevally — GT to anglers — are the largest members of the jack family. Adults reach 170 cm and over 80 kg. The body is deep and heavily muscled, silver in younger fish, darkening to charcoal grey or near-black in older dominant males. The head has a steeply sloping profile that gives the fish a bulldog-like appearance at size.
Distribution & Habitat
GTs range across the entire Indo-Pacific from East Africa to Hawaii, Japan, and French Polynesia. They patrol drop-offs, channels, and atoll lagoons, moving between reef structure and open water.
Behavior
These are among the most dominant reef predators in their range. They hunt by speed and ambush, often in small cooperative groups. On Farquhar Atoll in the Seychelles, GTs have been documented leaping from the water to snatch fledgling sooty terns from low flight — a behavior captured in the BBC's Blue Planet II. They eat almost anything they can catch, including small sharks and turtles.
Where to See Them
GTs are a classic sighting on Indo-Pacific current dives. Channel sites in the Maldives, Palau's Blue Corner, the Red Sea, and the Coral Sea deliver regular encounters. At baited shark dives they often dominate the action, chasing off smaller sharks to feed first.
Indo-Pacific: from East Africa to Hawaii and French Polynesia.
Apex reef predator. Hunts cooperatively and will attack from deep water at high speed. Famous for leaping to snatch fledgling terns from the surface.
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