Sooner or later many of us who pick up a fly rod would like to tangle with a GT, or Giant Trevally – Caranx Ignobilis. These are a brutally powerful fish that inhabit the tropical waters of the Pacific and Indian Oceans. In the Atlantic Ocean fly fishers can get a small taste of what’s in store for them by tangling with jack crevalle, which although a cousin to the GT and doesn’t grow anywhere near as large, pound for pound still pulls hard and is a full card carrying member of the trevally family, its only the regional name that’s different.

There are some 30 trevally species worldwide that are of varying degrees of interest to fly fishermen, and their habits and habitats are all reasonably similar. Many spend their lives in deeper water off reef edges and over deeper shoals and never come into the shallows; and some of them spend their lives in this same water, but fortunately for us, also get up onto the flats with varying levels of frequency from often to rarely.

If there’s one thing that’s common to this entire trevally tribe it’s a willingness to get into a fight. They mostly hang in schools so competition for food is fierce and they respond to a wide range of fly-fishing techniques. The GT is the big daddy of them. Although it would a fair call to say that the vast majority of the GT population never gets up onto the flats, more than enough of them leave the depths and the reef edges to cruise the shallows from time to time, and this makes them one of the great flats sight fishing species of the world.

They move into the shallows to hunt and to feed, sometimes as a single, especially the really big ones above 60lbs, and sometimes as a pack that could range anywhere from two to twenty fish and from 2 to 40lbs. Small packs of half a dozen big fish are also not uncommon. They visit the flats because that’s where the food so often is—mullet, bonefish, squid and other baitfish think they’re safe in the shallows, but the only safety they have is their numbers. GT’s feeding on the flats are rarely subtle, the best description would be that they are marauders, creators of mayhem and terror, they visit the flats with intent.

Off the edges of the reefs GT’s are found primarily in conjunction with a baitfish known as fusiliers and these are found on points where current or tide is hitting reef and creating upwellings. Fishing for GT’s off the reef edges in deeper water is usually done in conjunction with a hookless popper as a teaser, these are often the size of a bowling pin. They key is to get your fly out into the line of the retrieve the moment a fish hits the teaser, so the fish is brought to the fly. For this I use 10” flashy profiles and a Leviathan 26 ft sink tip line in 500 or 600 grains. Forget about throwing a popper on the fly rod, throwing one big enough far enough and fast enough to catch their attention won’t happen, whereas they can’t miss a sunken 10-12” flashy profile with a 10/0 hook in it.

But its on the flats where fishing for these monsters moves into another dimension that is at times off the planet. They can cruise the flats in water just deep enough to cover them, and often the bow wave they put up betrays them from hundreds of meters away. On a falling tide they can also wait in ambush in the flow in gutters and over little patches of reef and weed. These stationary fish are far more difficult to see because mostly we’re tuned into looking for movement from big black shapes.

I use RIO’s GT floater on a 12 Sage SALT, for me it’s a perfect GT set-up. Being designed for the job, this line is truly superb for long casts with big flies. Deceivers and squid patterns between 6 and 9 inches long tied on 6/0 and 8/0 hooks work fine as of course do the specialized GT patterns that have evolved. These are often dark flies that the fish can’t miss in the clear oceanic water of the flats.

Depending on the size of the fish and the water I’m in, I’ll fish 40-60lb fluorocarbon tippets. I like to lead the fish by around 15 feet and then start a fast retrieve right as the fish closes in on where the fly is, like its suddenly startled the bait. Do this and you can generate a reactive take and it also gives the fish little time to scrutinize the fly as the reaction is often spontaneous and the take invariably spectacular. Whack ‘em and whack ‘em hard again then stand by to clear the line. For laid up fish you want to be tight to the fly the moment it touches down. I’ll land it 6 feet in front of them but start stripping immediately to induce a reactive bite.

These fish don’t engage in any of that jumping, dancing, prancing energy wasting stuff, that’s for other fish that like to get up on the stage and perform; these brutal fish fight in a ring that has no ropes. A GT fight is an immensely powerful run and surge that takes them on a search for something to cut you off on—anything. It’s a battle of wills and the attitude to bring to this fight is to maintain a red line level of intense pressure; by doing this you can sometimes keep the upper hand early. With a very high level of pressure you can keep them distracted enough from looking for that lump of coral – they are not used to being bullied.

Give them their head freely early on and it will result in tears. If a GT gets any sort of opportunity to focus on looking for somewhere to cut your line, it will. Often the leader or fly line gets damaged on that first helter skelter run over the reef and past any bit of protruding coral – for this reason the 60lb core in the RIO GT line is vital as it can withstand some abuse and gives you a margin for wear and tear. If you stick it to them as hard as you possibly can right from the opening, and you can maintain that pressure, you can beat them.

I describe it as putting your foot on their throat and keeping it there, tarpon anglers talk about the same thing, the battle of wills, the need to dominate the fish – or you will probably lose. Unless there’s sand for as far as the eye can see you simply do not let a GT run, you’re not in this game to watch a reel spinning nicely or to admire the jumps– give them nothing, make them earn every inch- they will take it, but your task is to make it as difficult and as uncomfortable for that fish as you possibly can. Do that and you’ll win a few.

Peter Morse fishes with Nomad Expeditions on their mothership Odyssey. The northern outer Great Barrier Reef is one of the great wilderness destinations left on the planet with extensive flats and untold reef system to fish, it is a great adventure. Although specializing in popper fishing for GT’s they have several weeks a year that are dedicated to fly fishermen and GT’s can be caught both teasing and wading the flats.

The Seychelle Islands have the greatest GT flats fishing on the planet with guides who specialized in these fish on the flats.

Christmas Island in the Pacific Ocean also has outstanding fishing for GT’s so if you’re heading there don’t pack just your bonefish gear.