The “GT” in fishing circles refers to the Giant Trevally, a large marine fish. This powerful predator thrives in tropical waters, a prominent inhabitant of warm ocean environments. Known for its remarkable strength and aggressive nature, the Giant Trevally is a highly sought-after species by anglers worldwide.
Identifying the GT
The Giant Trevally (Caranx ignobilis) is the largest member of the Caranx genus within the jack family (Carangidae). It has a robust, moderately compressed body, with a more convex dorsal profile. A distinct feature is its large head with a steep profile and a prominent mouth. Its caudal fin is strongly forked, and the pectoral fins are sickle-shaped, extending longer than the head.
Giant Trevally exhibit a silvery coloration, though some may display dark spots. Mature males can become significantly darker, appearing dusky to jet black. A specific black spot at the base of the pectoral fins helps distinguish it from other trevally species. These fish can reach a maximum recorded length of 170 cm (67 inches) and a weight of 80 kg (176 pounds). While specimens over 50 kg are encountered in sportfishing, individuals exceeding 100 pounds are considered trophy catches.
This species is widely distributed throughout the tropical and subtropical Indo-Pacific region. Their habitat includes shallow bays, lagoons, deeper reefs, offshore atolls, and large embayments. Juveniles inhabit estuaries, coastal lakes, and the upper reaches of rivers, often preferring turbid waters. As they mature, they move to inshore and then outer reefs, often cruising along reef drop-offs in search of prey.
GT Behavior and Diet
Giant Trevally are apex predators, known for their aggressive and opportunistic hunting behaviors. They are powerful swimmers, capable of explosive strikes and reaching speeds over 37 miles per hour. While they can forage alone, they are also known to hunt in schools, sometimes coordinating with other large ocean predators like sharks or seals.
Their diet primarily consists of fish, but also includes crustaceans, cephalopods (like squid and octopus), and occasionally mollusks. Younger fish prefer crustaceans, such as stomatopods, shrimp, and crabs. Larger Giant Trevally are known to prey on eels, birds, and even juvenile turtles. Their feeding activity can vary by location, with some populations being most active during dawn and dusk, while others exhibit nocturnal habits.
GT as a Game Fish
The Giant Trevally holds a prominent status in sport fishing. Its strength, powerful runs, and relentless fighting spirit make it a challenging and rewarding target for anglers. Anglers employ techniques to pursue GTs, with casting large surface lures like poppers and stickbaits being popular methods, particularly near reefs and current breaks. Jigging, which involves rapidly retrieving metal jigs near deep drop-offs, is another effective technique.
While Giant Trevally are edible, their culinary appeal can vary. Smaller individuals (up to 5-6 kg) have white, firm, and mildly flavored flesh, making them suitable for consumption. However, the flesh of larger GTs can become very dry and tough, with a strong, fishy taste. A concern with consuming Giant Trevally, especially larger specimens, is the potential for ciguatera poisoning. This is caused by ciguatoxins, which accumulate in their tissues from consuming smaller reef fish that have ingested toxins produced by microscopic algae on coral reefs. These toxins are not destroyed by cooking or freezing, leading many anglers to practice catch-and-release, particularly for larger GTs.