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Top Tips On Catching Giant Trevally On The Fly

Top Tips On Catching Giant Trevally On The Fly

Over the years I have spoken to hundreds of customers about fly fishing for Giant Trevally, something many years ago everyone thought was crazy. As an all-round angler I first encountered these fish big game fishing at the Andaman Islands. I then moved on to try another method of fishing for them using poppers and jigs which was really starting to take off as a form of fishing in its own right. The popper fishing and jigging took us to places never fished before and this style of fishing gave us a really good understanding and experience of fishing for Giant Trevally’s. However, it was not long before we wondered what it would be like to try and hook and land these beats on fly gear.

Our initial fishing method was switch and tease, by taking the hooks off the poppers we found we could often draw in GT’s close enough to cast a fly from the boat. It took a lot of experimenting to learn the right techniques but the results were amazing, providing some great fights and an important insight on how to play GT’s on a fly rod. However, it still never felt quite right as saltwater fly fishing to me always seemed like hunting, so casting out lures to tease fish back to the boat started to lose its appeal.

It was on my first ever trip to Christmas Island many years ago when these fish really started to get under my skin. It was on this first trip that for the very first time I saw GT’s come and hunt on the flats. Boy oh boy little did I know what a game changer this was going to be. Now many years on I still love chasing down these fish, as the thrill as they chase your fly until you have only the leader left from the rod tip gets your heart racing before they smash you up.

Over the years I have gained a lot of knowledge and experience fishing for these fish and below I have shared some of the information I have learned in the hope that it also helps you be better prepared for your Giant Trevally adventures in hooking and landing more fish.

When Giant Trevally fishing consider the old saying, Fail to prepare = prepare to fail. If there is any weakness in your approach, tackle or methods Mr GT will exploit it, he will chew you up, spit you out, turn around and give you a good soaking just for good measure.

Mental Attitude

Firstly you have to decide whether you are going on a trip to fish for just GT’s or whether you are going on a saltwater fly fishing trip to fish for all species.

Why do I say this?

Well, it has to do with your realistic expectations. If you are going to fish hard for GT’s and nothing else, you will always be in the zone and prepared as you will only be carrying one rod and will also concentrate wading in areas that you will find the GT’s. If you’re only casting at GT’s while on a saltwater fly fishing trip, you will not always be wading/fishing in the right areas that GT’S can be found.

Sometimes GT’s only give you seconds of notice as they charge on a flat from a channel to only turn and charge back to deeper water. All this time you are focussing on trying to swap rods. Do not get me wrong I have caught some great GT’s fishing like this over the years and still today if I am saltwater flats fishing and there are GT’s around, I will always have a 12# rod with me. However if I have my serious Giant Trevally head on I will only take with me a 12# set up.

Realistic Expectations

Giant Trevally fly fishing is not for everyone as wading all day with a 12# set up, along with flats, edges of deep channels, the steep shoreline or wading into the surf crashing into a reef is hard work. Add to this casting large flies, dealing with strong winds and hard fighting fish, it can and does take its toll.

If you come expecting 20 plus shots a day at GTs this style of fishing is probably not for you. Realistically if you are purely hunting GT’s, 2 to 4 casting shots a day is what you should expect and is considered a good day. This is dependant on where in the world you are fishing but as an average, it’s a good guide.

Although Mr GT has the worse attitude of any fish he will not just jump any fly presentation, even when you think you’ve got everything right. Even the best GT anglers still have days where nothing has gone right. Therefore we always believe that each and every Giant Trevally caught and landed on a fly is worth celebrating, for it is such an achievement.


As previously mentioned, if you show any weakness then Mr GT will exploit it. Remember fly fishing is an art form that not everyone can master. It takes skill, patience, determination and knowledge. The right rod will make it a lot easier to cast large flies and have the power to land your catch.

12# fly rods are used to target Giant Trevally, together with a high-quality large arbour saltwater reel, with a strong smooth drag to match the 12# fly rod. The reel should be loaded with three hundred yards of 80lb braid and the majority of the time a tropical Giant Trevally floating fly line. I prefer the one that has an 80lb braided core running through it. Many times I have been playing a GT only to see when I am reeling in, parts of my fly line hanging off like a piece of spaghetti. If I wasn’t using a line with an 80lb braided core these would all have been lost fish. Believe me, if a GT gets near coral you need everything in your favour.

Good GT fly rods also have to have a good balance of power, you need flexibility in the top section of the rod so you can cast a line and large flies. You also need extreme power in the butt section to give you the ability to hold and pull fish away from the structure.

Best Tides For GT’S

I believe and have for a very long time that the best tide for GT’s is an incoming tide. GT’s like an incoming tide onto the flats as they have the knowledge that there is going to be plenty of water following them and that they will not get stranded. Also, on an incoming tide, the cool fresh water flows onto the shallow flats and many invertebrates such as crab, shrimp and worms leave their holes. In turn, this 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.

On an outgoing tide, especially as the tide is getting very low and shallow on the flats, there are always some low points, sometimes only 12 inches deeper than the surrounding flat which acts as small channels draining the water off the flats. If you find these places it is always good to stand at the end of them where they drain into a deeper channel as GT’s know that all the baitfish that have left things late will be coming off the flats down these channels. It can be a bit like a drive-in restaurant for GT’s so it’s always a good place to stand and cast flies.

Best Moon Phases For GT’S

Moon phase also affects tides as on both a new moon and a full moon you get a spring tide, which is the strongest tide. These spring tides, which are bigger so brings deeper water, allows the Giant Trevally to access areas that they cannot normally do on a neap tide.

I have personally found on big spring tides it brings more GT’s from the deeper water to hunt on the shallow flats and therefore gives the angler more opportunities. If I had to pick just one time to fish, for me it would always be on a new moon, in others words no moon. The reasoning is quite simple, a new moon brings spring tides and good water, however as there is no moon GT’s cannot hunt at night. If you look closely at a GT you will see they have large black eyes, perfectly designed for seeing prey in low light conditions like moonlight. This gives GT’s an advantage in being able to hunt and feed in low light when the prey struggle to see them coming.  Therefore on moonless nights GT’s will not be feeding so come morning all the GT’s you encounter are going to be aggressive and super hungry.

Casting for GT’S

If I can refer you to the beginning, fishing for GT’s is all about being prepared. I always advise customers, unless they have lots of experience casting 12# rods with big flies, to take some lessons.

If you think you are up to it, go and find some water or even a park field and practice. Go on a windy day, cast with the wind in your back and cast with the wind on your side. If you are right handed try and cast with the wind pushing into your right shoulder (make sure you have a big fly but take off the point of the hook). You will soon realise that you will hit yourself if you do not know how to fish effectively with the wind on your side.

Additionally, try casting directly into the wind and even backcasting. All this practice will only help when all the action happens. The next thing to practice is wading ready to cast, so you can react fast, and I mean fast! Sometimes you fall lucky and you get to spot Mr GT swimming along making his way down to you, so you have all the time in the word to get ready. However, most times you spot Mr GT you have to wade or even run to intercept them all at the same time as getting out the line and casting a fly.

The trick is easy, ALWAYS have the line stripped off the reel. Have the coils of different lengths hanging from your casting hand finder tips. Hold the end of the loops in your left hand. Also have as much of a D loop hanging from your rod to your fly which is lightly hooked into your cork handle.  This way when you spot a fish you throw the end of the line in your left hand out to the left while at the same time allowing the coils to fall from your fingers. This now means all your casting line is around your feet in the water tangle free. Unhook your fly, throw it forward while rolling your rod so you make a forward roll cast. Now as you lift the rod to start to make your cast the rod will load quicker as you will be lifting line from the water. One or 2 false casts is all you should need.

Listen To Your Guide

When you spot a Giant Trevally it is crucial to remain calm, which is a lot easier said than done. Listen to your guide and move into position quickly whilst trying not to make too much noise. When your guide calls for you to make the cast try and lead the fish by 3 -4 rod lengths, this is a good rule of thumb. If the fly lands on the head or behind the GT, the chances of the fish eating are almost none.

Once the fly has been presented you need to start a long and fast retrieve. I always teach my customers that you have to strip like you do not want the GT to grab your fly. Treat it as a competition, try as hard as you can to not let him eat it and then 90% of the time he will. If you get too excited as it gets closer, don’t slow up as you want the GT to eat your fly, if you do he will turn away as no baitfish being chased by a GT will ever slow down as it swims for its life. The GT may be aggressive but is no fool.

Setting the Hook

When a Giant Trevally eats your fly keep the rod tip pointing down and pointing at the fish. You will have to set the hook with what is called a strip strike. As you are stripping you will have the rod in your right hand and the line you are stripping in your left hand. As the Giant Trevally eats the fly, hold on tight to BOTH the rod and the running line in your left hand, simultaneously pull as hard as you can with both hands while pointing the rod at the fish. 2 or 3 sharp pulls as hard as you can (you will not snap off) backwards with both hands will be enough to set that hook. Once the hook is in you can release your hold on the line in your left hand. Once all the spare line around your feet has run out and the line is now pouring off the reel, you can now lift the rod.

Playing GT’S on the Fly

It is at this point when you are going to feel the unleashed power of a Giant Trevally. These fish are going to take long powerful runs, however, you need to break these runs as quick as possible.

A simple rule: the more line that’s between you and the GT, the higher the percentage of losing that fish increases dramatically. Once the fish is roaring off, start to clamp up the drag, keep increasing until you feel like you cannot physically hold on to the rod any longer. Many people are scared to apply so much drag on these fish, but you will be surprised at how much you can apply (on my reels which have had some abuse I admit, I tighten them to the max and still increase the pressure buy palming the spool as well).

One thing we learnt in the very early days was that you have to break the GT’s spirit and you cannot hurt a GT playing it with your rod up in the air. Remember to always apply side strain and constantly keep changing sides. When the GT pulls hard to the right, you need to pull hard from the left, once the GT is more square on change angles and pull him from the opposite direction.

You need to gain line back as quick as possible so pump and wind, no lifting up the rod, just pull to the side keeping the rod below 45 degrees and wind as the rod moves forward. This means you are giving the fish what we call the butt of the rod which is where the power is. It is this combination of constant change of direction and powerful pulling back that breaks a GT’s spirit. Before long the GT will be turning on its side for once you can get them on to their side they clam down and it is now when your guide can tail your fish.

Enjoy Your Catch

Once your guide grabs the tail of your fish you will be screaming, punching the air and wanting to hug everyone in the world, and so you should be. As mentioned right at the beginning, each and every landed GT regardless of size should be appreciated, for now, you know why you spent all that money on the tackle, travelled around the world, waded miles of saltwater flats and spent weeks practising your casting. Welcome to the world of catching GT’s on the fly.

Want To Learn More?

You can learn more about GT fishing by watching my Fly Fishing For GT’s video on Youtube. This video shows how to cast, hook and land these amazing fish.

If you have ever wanted to catch GT’S on the fly we host group trips every year. To learn more contact our team, they will help find the perfect fishing destination for you.

Tight Lines,


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