Conquer the Challenge: Fly Fishing for Giant Trevally

Hunting giant trevally with a fly rod has to be the pinnacle of fly fishing for saltwater fish species as they are one of the largest fish you can catch sight fishing o the flats along with tarpon.

Having guided in Seychelles for giant trevally I can tell you they do not compare to any other species you can fly fish for. The sheer aggression when a cruising GT turns on to your fly makes your legs shake and when the fish eats and runs, your heart everything but explodes.

However, giant trevally fly fishing isn’t easy and it’s not for the faint-hearted angler either. In most cases, you’ll need to go on a fishing trip to a remote part of the world to have the chance of casting a fly to one and then success still isn’t guaranteed hence why I’m writing this article.

Your best chance of success when GT fishing is being prepared for the task and I run through everything you need to know below.

What are giant trevally and where do they live?

What are giant trevally and where do they live

Giant trevally, or GTs, live in the tropical waters of the Pacific and the Indian Ocean. You can find them all the way from the coast of Kenya to South America but most GT destinations for fly fishing tend to be on remote offshore atolls such as Seychelles. And of course expect these GTs when your fly fishing christmas island.

Giant trevally are a part of the jack family and are often referred to as barrier trevally, lowly trevally, and giant kingfish in some parts of the world, mainly South Africa. They are an apex predator that frequent every part of the marine ecosystem around deeper reefs and shorelines.

They are usually silver in color with occasional dark spots but they can be black and change color from black to silver depending on their mood. They can grow up to 140cm+ in length and weigh over 100lbs but the average giant trevally is around 75 cm and small trevally around 50cm.

GTs will sit in deeper waters when the bait is there. On a pushing tide, they run out of the deeper water across surf areas and onto shallow flats to eat bonefish and mullet and even make their way into shallow bays and coastal lakes with very low salinity.

Exactly what fly fishers love about these fish is their attitude. A GT’s attitude is that it is the boss. A GT will go after anything – I have seen a group of GTs trying to eat a small shark, so when one decides to eat your fly, you know about it.

What do giant trevally eat?

What flies do I need for catching GTs

As I said above, giant trevally will go after anything but a GT’s main diet consists of small baitfish species such as mullet, bonefish, emperors, and lots more but they will also eat invertebrate species such as crabs and shrimps too.

They also eat birds – as you probably saw on the first episode of Blue Planet II, which means they can track things in the air – just think about your fly for a second in that regard.

What gear is needed for giant trevally fly fishing?

When you’re fly fishing for GTs you’re using some of the heaviest gear fly fishing has to offer. This is not only because you’re going up against an immensely powerful fish but also because you’re catching them around sharp coral and you need to stop them before they break you off.

The ideal surf fly fishing setup for GTs is as follows:

  • 12 weight fast action fly rods
  • 12 weight saltwater reel with an excellent drag
  • 300 yards of 80lb backing
  • A 12 weight floating fly line with a 50lb plus core
  • 80-100 lb fluorocarbon leader
  • A range of GT flies

As you can see, you don’t mess around when trying to catch a GT. You should always carry a spare 12 wt fly line with you when fishing the flats for GTs as they can destroy a fly line in a few seconds rendering it useless for the rest of the day.

What flies do I need for catching GTs?

What do giant trevally eat

When fishing for giant trevally you will be using big flies and will want a selection of brush flies and poppers with you on the flats as these imitate baitfish species perfectly.

A few NYAPs (not your average popper) in different colors (black and white) are essential as well as some double-barrelled poppers too.

Make sure to have a purple and black brush fly, a red brush fly, and a green brush fly to imitate fish species that live on the reef and in lagoons. You should also carry a tan brush fly or two in order to imitate the flats bait species like bonefish and mullet.

Casting Practice Is Very Important

Not everyone knows how hard it is to feed a fly to a GT, and if you haven’t practiced casting or know how to double haul fly cast, you’re going to struggle.

Most anglers haven’t ever cast a 12 weight fly rod in their lives and some anglers show up in Seychelles expecting to learn how to double haul a 12 wt on the job.

It usually takes anglers a week (their entire trip to the Indian Ocean) to get to grips with casting such a heavy rod and this means most of their GT catching opportunities from days 1-5 go wrong.

Make sure you learn to double haul and cast your 12 wt every day for a month before going to any GT destinations. You should aim to be throwing your fly onto a plate around 60-70 feet away. If you do this, you have a chance of hooking the first GT you see on the flats.

Catching a GT – How is it going to go down?

Catching a GT

Catching a GT isn’t easy and being prepared for how it might happen is the best way to be ready for probably the most intense fishing experience the world has to offer. It pays to watch some videos of fly anglers catching GTs so you know what you’re up against too.

Setting The Scene

When looking for GTs you’ll either be wading in the surf or on the flats or being poled on the flats by your guide. The location you’re fishing in will be dependent on the tide and your fitness, as walking in the surf is very demanding on your body.

While you’re wading or being poled on the flats you should have a rod length of fly line out of the rod, enough line stripped out for a 60 ft cast, and have your fly in your hand ready to go.

What Do I Do When I See a Giant Trevally?

What Do I Do When I See a Giant Trevally

Chances are your guide will spot the fish before you and when you’re fishing with a guide, it’s best to fish with your ears – ie listen to your guide. They will tell you where and when to cast.

Once you see a GT or your guide sees GT and tells you about it, the first thing you should do is get your eyes on the fish and then take a deep breath to try to remain calm.

GT’s seem to insight panic into anglers and for good reason, and 90% of opportunities are missed because people choke – and we all do it, guides included.

Now think about where the fish is heading and where you want to cast your fly so it might feel like eating it.

Where should I cast my fly to a giant trevally?

As I mentioned earlier, birds are a part of a GT’s diet which means they have excellent eyesight. No fish ever in the history of the ocean swam up to a GT and jumped on its head, so don’t cast the fly there.

You want your fly to land around two rods length or a stone’s throw in front of the fish so it can chase it.

Stripping, Setting, and Fighting

Some GT’s like a fast stripped fly, others like a slowly stripped fly. Once your fly lands wait for it to sink a bit until the GT is around 10 feet from it.

Start with a slow long strip pulling the fly line as far back as possible and pushing your rod forwards at the same time. If the fish accelerates, match it and start stripping fast, if not stay slow.

When the fish takes, keep stripping to set the hook and set it hard. Then keep your rod down as it pulls line and comes onto the reel. Be sure to clear your line without any tangles. Once the fish is taking line, tighten your drag to the max and then start fighting it.

Never lift your rod tip above your eye line during the fight, short lifts are all that’s needed. After 5-15 minutes, you’ll have the fish to hand.

Where are the best GT fly fishing destinations in the world?

Where are the best GT fly fishing destinations in the world

The best GT fly fishing destinations are Christmas island and on the atolls of Seychelles in the Indian Ocean.

The best GT fishing on the planet is on Cosmoledo Atoll in the Indian Ocean which is part of Seychelles. There is a world-class guiding operation there and one can catch 20 GTs on a fly in a day if you are lucky.

You can also fish the atolls of Poivre, St Francois, Alphonse, Astove, Faquahar, Providence, and the most southerly atoll of Saint Brandon.

If you really want to catch a GT on the fly then you should contact my old bosses at Alphonse Fishing Company as they run the fishing lodges on almost all the atolls mentioned above.

Photo of author

Jamie Melvin

Growing up fly fishing on trout streams in Kenya and the UK, Jamie has traveled the world in search of fly fishing nirvana. From his time managing bonefish lodges in the Bahamas and running fishing safaris in East Africa, all the way to guiding on the flats of Seychelles, there aren't many species or environments he hasn't experienced firsthand.

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