Giant Trevally Fly Fishing

Targeting giant trevallies on the fly is not for the faint-hearted angler. They are fierce, big, aggressive, and incredibly powerful. They are also quite often completely underestimated by new anglers but are respected by new and seasoned fishermen alike. You need more than the best giant trevally flies, the best fly fishing rods, and ideal conditions to catch giant trevally – they have earned their name as ‘the gangsta’s of the flats’ for a good reason!

Giant trevally fish have a reputation for being thugs, bullish and unforgiving. They prey on almost anything that moves. From crabs, lobsters, squid, and eels to mantis shrimps. However, their favourite prey are be the wide variety of smaller fish that populate the shallow flats. Which mainly consist of shoaling fish like mullet, bonefish, smaller trevally species like brassy trevally, and even small power lips.

Key Facts About Giant Trevally

The length of an average giant trevally

Giant Trevally Average Length

85 cm

The weight of a Giant Trevally

Giant Trevally Average Weight

15 kg

The diet of a Giant Trevally

Giant Trevally Diet


Giant Trevally growth phrase

Giant Trevally Time to Maturity

3 – 4 years

The average age of a Giant Trevally

Giant Trevally Average Age

6 – 7 years

Fly Fishing

The Search For Giant Trevally

It’s not uncommon to hook giant trevallies while trawling for tuna, wahoo, and sailfish in the deep blue. Conversely, giant trevallies are known to be caught in depths exceeding 80 m. In contrast, for fly fishermen the most appealing way to hook a GTs is wading in knee-deep water on the flats. The varying depths GT are found in prove that they are apex predators.

Best Giant Trevally Flies


The black brush fly has probably taken down more GT fish than any other fly that we use. The combination of adding a hint of purple, red, or olive to the black brush fly also works really well. Keith often gets asked by guests: “What fly works the best?” His standard reply is: “You can use any fly you want, as long as its a black brush fly!”


The olive and red semper fly, like all semper patterns, have an incredible movement in the water. The thin hackles in the tail, the marabou collar, and the EP Brush head, provide this fly with incredible action in the water. These flies are irresistible to any cruising giant trevally. 


Traditional popper patterns are becoming popular as they create a greater disturbance on the water. Poppers are generally fished over deeper waters, such as drifting on the skiff in the lagoons, casting into the channels, and floating on the shallow outer reef of the atolls. Be sure to have this one ready too.

Best Giant Trevally Rod Set Up

Everything about GTs screams ‘big’. Big fight, big flies, big fish, so naturally, you need a big rod too, therefore 12 weight fly rods are used to target giant trevally. Your rod needs to be paired with a high-quality large arbour saltwater series reel with a strong, smooth drag to match. The reel should be loaded with three hundred yards of 80 lbs braid. Once hooked, these fish love to head straight for the coral or drop off into the deeper water, which often results in a lost fish. Having a good fishing rod that you can pull very hard is necessary, therefore, any rod with a strong butt section is recommended.

Best Tides For Giant Trevally

Pushing tides are considered to be the best time to target a GT. The fish know that they have plenty of water pushing behind them on the flats and are more at ease to avoid getting trapped, as opposed to a dropping tide. As the cool freshwater flows onto the shallow flats, many invertebrates such as crab, shrimp, and worms leave their holes. This, in turn, brings bonefish and other small fish onto the flats to feed, and the chain continues up to the bigger predatory fish like the giant trevally.

Making The Catch

Once you spot a giant trevally, it is crucial to remain calm and listen to your guide. Move into position quickly, trying not to make too much noise and keeping your fly line clear of any potential snags. Under the guide’s instruction, make the cast. Generally, leading the fish by three to four rod lengths is good. If the fly lands on the head or behind the GT, the chances of the fish eating it are almost none. Once the fly is presented, a long and fast retrieve is necessary. 

Once the fish eats the fly, keep the rod tip pointing down, and set the hook by strip/line setting.

Lifting the rod in an attempt to set the hook is not effective and gets the hairs on the back of your guide’s neck to stand on end. Only once the giant trevally is on the reel can you lift the rod and fight. And to be clear, you need to get ready for one hell of a fight!

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