Learning how to catch Giant Trevally on the fly is one of the toughest but most rewarding challenges in saltwater fly fishing. These fish are powerful, aggressive, and completely unforgiving of mistakes, which is exactly what makes them so addictive to target.
This guide has been developed by our CEO, Peter Collingsworth, a highly experienced and well-travelled fly fisherman with decades of experience targeting some of the world’s most challenging species.
Having fished extensively across destinations such as the Christmas Island and other leading saltwater fly fishing locations, his knowledge has been built through years of hands-on experience in demanding conditions.
His approach to Giant Trevally fly fishing focuses on preparation, precision, and understanding fish behaviour, principles that underpin the advice shared throughout this guide.
In this guide, I’ll break down everything you need to know, including:
- The best tides and moon phases
- Essential tackle setup
- Casting and presentation tips
- How to maximise your chances when that moment finally comes
Over the years, I’ve spent countless hours targeting Giant Trevally across destinations like Christmas Island and the Andaman Islands, refining techniques and learning what truly works when it comes to consistently hooking and landing these fish.
Because with Giant Trevally, preparation is everything.
Table of Contents
- What Makes Giant Trevally So Challenging
- GT Fishing Expectations (What to Expect)
- Essential Tackle for Giant Trevally
- Best Tides for Giant Trevally
- Best Moon Phases for GT Fishing
- Casting for Giant Trevally
- Listen to your Guide
- Presentation, Hooking, and Playing.
Early approaches to targeting Giant Trevally on the fly often involved a “switch and tease” method, using hookless poppers to draw fish close enough to present a fly. While effective, this approach relied heavily on boat positioning and did not fully capture what saltwater fly fishing is really about.
True fly fishing for Giant Trevally is far more visual and immersive. It involves spotting fish on the flats, anticipating their movement, and presenting a fly with precision, often in just a few seconds. It’s a style of fishing that feels far more like hunting than traditional lure fishing.
Destinations such as Christmas Island have played a major role in shaping this approach. Watching Giant Trevally move onto the flats to hunt for the first time is a defining moment for many anglers, completely changing how these fish are targeted.
From that point on, the appeal becomes clear. The visual takes, aggressive follows, and explosive power of these fish create one of the most adrenaline-driven experiences in saltwater fly fishing.
However, one thing becomes apparent very quickly:
Preparation is everything.
When targeting Giant Trevally, even the smallest weakness in tackle, approach, or execution will be exposed. These fish are unforgiving, and success comes down to being ready for the moment when it happens.
Mental Approach to Catching Giant Trevally
Success when learning how to catch Giant Trevally on the fly starts with mindset and expectations.
The first decision is simple but important:
👉 Are you targeting Giant Trevally specifically, or fishing for multiple species?
When focusing solely on GT’s:
- You stay prepared at all times
- You fish the correct water
- You maximise every opportunity
When fishing for multiple species, attention is divided. This often means spending less time in prime GT water and being unprepared when opportunities arise.
Because with Giant Trevally, opportunities are often brief.
Fish can appear suddenly, charge across a flat, and disappear just as quickly. In those few seconds, there is only time for one well-executed cast. If the line isn’t ready or the rod isn’t set up, the opportunity is gone.
This is why serious GT anglers commit fully to the approach. A single 12-weight setup, ready at all times, ensures you are always prepared when that moment happens.
What to Expect When Fly Fishing for Giant Trevally
Targeting Giant Trevally on the fly is physically demanding and mentally intense. Long days wading across flats, navigating deep channels, casting large flies into strong winds, and dealing with incredibly powerful fish all take their toll.
This style of fishing is not about numbers.
Anglers expecting 20 or more opportunities a day will likely be disappointed. When specifically targeting GT’s, 2 to 4 shots per day is considered a good result, depending on location and conditions.
Even when everything is done correctly, Giant Trevally are far from predictable. They often follow a fly only to refuse at the last moment, and even experienced anglers can have days where nothing quite comes together.
That’s what makes it so addictive.
Every fish is earned through effort, timing, and execution. The reward comes not from quantity, but from the intensity of the experience, the hunt, the presentation, the take, and the battle that follows.
Explore our Giant Trevally fly fishing destinations to find the right location for your experience level.
Essential Tackle for Giant Trevally Fly Fishing
When learning how to catch Giant Trevally on the fly, having the right tackle is critical. These fish are incredibly powerful, and even the smallest weakness in your setup will quickly be exposed.
Rod and Reel Setup
A 12-weight fly rod is the standard choice for targeting Giant Trevally. It provides the necessary power to cast large flies in windy conditions, while also giving you the strength needed to control fish and pull them away from coral and structure.
This should be paired with a high-quality large arbor saltwater reel, featuring a strong, smooth drag system capable of handling fast, powerful runs.
Line and Backing
Reels should be loaded with around 300 yards of 80lb braided backing, combined with a tropical fly line designed specifically for GT fishing.
A fly line with a reinforced core (around 80lb) is highly recommended. Under pressure, standard fly lines can fail, especially when fish get close to coral or structure. A stronger core significantly reduces the risk of losing fish during the fight.
Balance and Performance
A well-balanced setup is essential. The rod must have enough flexibility in the tip section to cast effectively, while maintaining maximum power through the butt section to apply pressure when it matters most.
Modern fast-action travel rods have made a significant difference in this style of fishing, offering both casting performance and lifting power when fighting larger fish.
If you’re unsure about your setup, our team can help you prepare for your trip.
Best Tides for Giant Trevally Fly Fishing
Understanding tides is key when learning how to catch Giant Trevally on the fly, as they directly influence fish movement and feeding behaviour.
Incoming Tide
An incoming tide is generally the most productive. As water pushes onto the flats, it creates ideal hunting conditions for GT’s.
- Rising water gives fish confidence to move shallow
- Cooler water flows onto the flats
- Crabs, shrimp, and worms become active
- Baitfish such as Bonefish move in to feed
This chain reaction attracts Giant Trevally, making the incoming tide one of the best times to target them in shallow water.
Outgoing Tide
An outgoing tide can also be effective, particularly as water begins to drain off the flats.
As the tide drops, small depressions and natural channels form, often just slightly deeper than the surrounding flat. These act as funnels, pushing baitfish back toward deeper water.
Positioning yourself where these channels meet deeper drop-offs can be highly productive, as GT’s often wait here to ambush prey moving off the flats.
Best Moon Phases for Giant Trevally Fly Fishing
Moon phases play an important role in how to catch Giant Trevally on the fly, as they directly influence tidal movement and feeding behaviour.
Spring Tides (New & Full Moon)
During both the new moon and full moon, larger spring tides occur. These stronger tides push more water onto the flats, allowing Giant Trevally to access areas that are often unreachable during smaller neap tides.
This increased water movement:
- Expands feeding zones
- Brings more baitfish onto the flats
- Creates more opportunities for anglers
Why the New Moon Stands Out
While both moon phases can produce results, the new moon is often considered the most productive.
With little to no moonlight at night:
- GT’s have reduced visibility when hunting
- Feeding activity overnight is often lower
- Fish are typically more aggressive during daylight hours
By contrast, during brighter nights, Giant Trevally can feed more actively under low-light conditions, which can reduce their urgency to hunt during the day.
Casting for Giant Trevally on the Fly
When learning how to catch Giant Trevally on the fly, casting is one of the most critical skills to master. Opportunities are often brief, and success depends on being able to react quickly and deliver an accurate cast under pressure.
Practice Before You Travel
Casting large flies on a 12-weight setup in windy conditions is demanding. Anglers without experience should strongly consider lessons before travelling.
Practising in different conditions is essential:
- calm conditions to build technique
- casting with the wind behind you
- casting with the wind on your shoulder
- casting directly into the wind
This helps prepare for the realities of fishing on the flats, where wind and pressure are constant factors.
Be Ready at All Times
When a Giant Trevally appears, there is rarely time to prepare.
Fish can move quickly across the flats, often giving only seconds to react. Being ready to cast at all times is essential, especially when moving between areas or wading into position.
Line Management is Key
One of the most important aspects of GT fly fishing is managing your line effectively.
Before spotting a fish:
- Have your line already stripped off the reel
- Keep loose coils organised and tangle-free
- Ensure your fly is ready to go
When a fish is spotted, the goal is to get the line into the water quickly and cleanly, allowing for an immediate cast without tangles or delays.
A simple and effective approach is to drop the line cleanly into the water while beginning your cast, using a roll cast to load the rod before making one or two controlled false casts.
Speed and control are far more important than distance. For more detailed guidance, read our blog on managing your running line.
Giant Trevally Fly Fishing: Listen to Your Guide
When learning how to catch Giant Trevally on the fly, one of the most important factors is working closely with your guide.
Positioning and the Cast
When a fish is spotted, staying calm is essential. Move into position quickly and quietly, following your guide’s instructions.
A good rule of thumb is to lead the fish by 3–4 rod lengths. Although GT’s are aggressive, accuracy is critical. A fly landing too close, on top of the fish, or behind it will almost always result in a refusal.
The Retrieve
Once the fly is presented, the retrieve needs to be fast, consistent, and deliberate.
The key is to imitate a fleeing baitfish:
- Long, powerful strips
- No hesitation
- No slowing down
If the retrieve slows as the fish approaches, the GT will often turn away. In reality, prey never slows down when being chased, and neither should your fly.
The Take and Hook Set
When a Giant Trevally commits, everything happens quickly.
- Keep the rod tip low and pointing directly at the fish
- Do not lift the rod
- Set the hook using a strip strike
A strong strip strike involves pulling firmly with the line hand while maintaining pressure with the rod hand. Two or three powerful pulls are usually enough to set the hook securely.
Once the hook is set and the line clears, the reel takes over, and the fight begins.
Playing Giant Trevally on the Fly
Once you’ve learned how to catch Giant Trevally on the fly, the next challenge is landing them. This is where many fish are lost.
Giant Trevally are incredibly powerful, and controlling the fight early is critical.
Control the First Run
After the hook-up, expect a long, powerful initial run. The key is to apply pressure quickly.
- Increase drag steadily
- Apply as much pressure as you can comfortably handle
- Avoid giving the fish too much line
The more line between you and the fish, the greater the risk of losing it to coral or structure.
Use Maximum Pressure
Many anglers are hesitant to apply heavy drag, but GT fishing requires confidence.
- Don’t be afraid to push your tackle
- Apply additional pressure if needed
- Stay in control at all times
These fish are built for power, and the fight must be managed from the start.
Use the Rod Correctly
A common mistake is fighting the fish with the rod held high.
- Keep the rod low, below 45 degrees
- Apply pressure through the butt section
- Avoid relying on the tip for power
The strength of the rod comes from the lower section, and using it correctly makes a significant difference.
Apply Side Pressure
Constantly changing angles is key to breaking the fish’s strength.
- Pull from the opposite direction of the fish
- Switch sides regularly
- Keep the fish off balance
This prevents the fish from settling into a steady, powerful run.
Pump and Wind Efficiently
To regain control:
- Pull to the side using the rod
- Wind down as you lower the rod
- Maintain constant pressure
This technique allows you to recover line quickly while staying in control of the fight.
The Final Stage
As pressure builds, the fish will begin to tire.
Once a Giant Trevally turns onto its side, the fight is effectively under control. At this point, your guide can move in to land the fish safely.
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, 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. We hope you took away some tips on how to catch Giant Trevally on the fly.
Contact us
You can learn more about how to catch Giant Trevally 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, you can contact me anytime in the office by calling 01603 407596 or by emailing peter@sportquestholidays.com.
