Giant trevally (GT) (Caranx ignobilis)

Photo by Christopher Mark on iNaturalist · CC BY 4.0

FishActive now (October)

Giant trevally (GT)

Caranx ignobilis

When
Active all year, though the way you fish or find it changes with the season.
Where it holds
Coral reefs, reef channels, atoll flats and surf from the Red Sea down the East African coast to South Africa, and around the Seychelles and Madagascar. Young fish live in estuaries.
How to know it
A thick, powerful jack with a steep, blunt head, hard scutes along the base of the tail, and silver-grey to black colouring; mature males can be almost black.
What to know
The bully of the reef and a bucket-list fish on fly, above all on the outer atolls of the Seychelles. Most sport-caught GTs are now released.
The tactic
Big poppers and stickbaits worked hard over reef edges and channels; on the flats, a big baitfish fly on a 12-weight.
Caution
Large GTs can carry ciguatera toxin — one more reason to let them go.

Seasons, size limits and catch limits change every year and differ by water body. Check the current regulations for the country and the water before you fish.

Giant trevally (GT) facts

Also called
GT; giant kingfish in South Africa; ulua in Hawaii; also lowly or barrier trevally.
Family
Carangidae, the jacks and trevallies. The largest of the Caranx jacks.
Native range
The tropical Indo-Pacific: from the Red Sea and the whole East African coast to South Africa, across the Indian Ocean islands — the Seychelles, Madagascar, the Maldives — and east to Japan, Australia and Hawaii.
Habitat
Young fish in estuaries, shallow bays and lagoons, often in murky water; adults on reefs, reef channels, atolls and offshore banks, alone or in pairs. Off South Africa it hunts mostly by day, especially at dawn and dusk.
Water temperature
Tropical: FishBase gives 26–29°C (79–84°F).
Size
Most adults 60–120 cm (24–47 in); the largest measured about 170 cm (67 in).
Record
IGFA all-tackle world record: 72.8 kg (160 lb 7 oz), Keiki Hamasaki, Tokara, Kagoshima, Japan, 22 May 2006.
Lifespan
Growth studies suggest a 1 m fish is about 8 years old and a 1.7 m giant about 24.
What it eats
Mostly fish, including eels, plus squid, octopus, mantis shrimp, crabs and lobsters.
Spawning
In southern Africa from July to March, peaking November to March, in schools gathering over reefs and banks at set phases of the moon. It matures at about 60 cm and three years old.
Young fish
Larvae are silver with six dark bars. Juveniles live in estuaries, even in nearly fresh water, before moving out to reefs.
Teeth and mouth
A big, strong mouth with small teeth; the steep, blunt forehead is the giveaway.
Look-alikes
Bluefin trevally is smaller, with electric-blue fins and dark spots. Bigeye and brassy trevally are smaller, and the bigeye has the bigger eye. A GT’s steep head, sheer bulk and naked breast with a small patch of scales in front of the belly fins set it apart.
Eating
Rated anything from poor to excellent, but big fish can carry ciguatera toxin, so large GTs are best released.
Status
Least Concern on the IUCN Red List.

Try it

How big does a giant trevally get?

Slide it from an ordinary adult to the biggest one ever measured, next to things you know the size of.

90 cm · 35 inmost adults20406080100120140160180200cm122436486072ina 4-year-old, lying down · 100 cma canoe paddle · 150 cma grown-up, lying down · 170 cm

Most adults you'll catch: 60–120 cm (24–47 in).

This giant trevally (gt): 90 cm. Longer than a loaf of bread, shorter than a four-year-old.

The record

IGFA all-tackle world record: 72.8 kg (160 lb 7 oz), Keiki Hamasaki, Tokara, Kagoshima, Japan, 22 May 2006.

Questions people ask about giant trevally

Where can you catch a giant trevally in Africa?

Along the whole east coast, from the Red Sea through Kenya, Tanzania and Mozambique to KwaZulu-Natal, and above all around the Indian Ocean islands. The remote outer atolls of the Seychelles are among the most famous places in the world to catch one on fly.

How big do giant trevally get?

Up to 1.7 m (5 ft 7 in) and about 80 kg (176 lb). The IGFA all-tackle world record is 72.8 kg (160 lb 7 oz), from Japan in 2006.

Can you eat giant trevally?

Small ones, carefully. Large GTs are a known source of ciguatera, a fish poisoning from reef toxins that builds up the food chain. Most anglers release them, and catch-and-release is increasingly the norm.

Found in these regions

Checked against these sources ·

Sizes, records and ranges are for the species as a whole; local fish, and local rules, vary. Records change — the record-keeper named above has the current one.

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