Ask most anglers what the ultimate game fish is, and you’ll hear a resounding answer of billfish. Since the early days of offshore fishing, these incredible creatures have captivated the minds of fishermen, writers, and artists. Yet billfish is not a single species of fish but rather a classification of pelagic species with long, slender bills. This grouping includes sailfish, blue marlin, black marlin, and striped marlin, all of which can be found in Costa Rica. Of the places in the world to fish for billfish, few offer more in terms of diversity than Costa Rica. We began our Coast to Coast expedition fishing the blue water of the Pacific in hopes of raising billfish from the deep and catching them on fly. Here’s everything we did to make it happen.
Bring the Right Gear
When targeting billfish, the first step is to bring the right gear. Billfish, like marlin, can reach sizes of over 1,000 pounds. While you won’t be landing fish that big on the fly, even a fish a fraction of that size will put your gear to the test. For rods, we recommend a 12-wt for smaller sailfish, and at least a 15-wt for marlin. These rods definitely fall into the broomstick category, but that’s alright. They are designed for fighting fish, not casting. Keep both rods rigged and ready in case a billfish sneaks into the spread.
Once you’ve settled on rods, it’s time to find the proper fly reel. For starters, look for reels that can hold a lot of backing. You’ll want at least 350 yards to tame long and powerful runs that marlin are known for. In addition to line capacity, you’ll want a smooth drag. This is particularly important for fighting big fish on light line. When a big billfish is greyhounding through the air and dragging your fly line behind it, too much pressure or a clunky drag can pop the fish off.
The next step is prepping your setup for billfish. To achieve a bulletproof connection to a fish, knots are key. Load your reel up with 65-pound gel-spun backing and finish it off with a double bimini twist. If you don’t know how to do this, bring it to a local fly shop that can properly tie these knots and set up your reel.
Troll, Troll, and Troll
In Costa Rica, like many billfish fisheries, the key to finding fish is trolling. Typically, a boat will troll teasers behind it, at a slow and steady pace. These are often lures or dead baits that imitate a school of fleeing fish from below. When a marlin sees it, they’ll head off the bottom towards the surface for a closer look. It’s also worth noting that certain boats can raise more fish than others. The most common theory is that certain boats and motors emit a vibration that draws billfish in, while others may actually repel fish.
Typically, boats will troll around ledges, FADs (fish attracting devices), and bait schools in hopes they come across billfish. In Costa Rica, you can also occasionally come across schools of billfish, mainly sailfish, attacking bait on the surface. If that’s the case, get ready for some epic sight casting.
Stay Attentive
The monotony of trolling for hours, the hum of the engine, and a warm breeze are a recipe for dozing off. However, attention is critical when billfishing. At any moment, a fish can appear in the spread, and if the crew and angler are not paying attention, your opportunity is gone. If you have multiple anglers, consider switching throughout the day. This will give you fresh eyes on the spread and the focus needed to be ready at a moment’s notice.
Keep Your Fly in the Water
When the time comes and you watch the dorsal fin of a billfish ripping through your spread, it’s time to make your shot count. The trolling spread will be yanked out of the way by the crew, giving you the opportunity to throw your fly into a clear boat wash. While this happens, one of the mates is typically designated as the teaser. Their job is to work a hookless bait across the surface, get the marlins’ attention, and bring them closer to the boat. While this is happening, get your fly in the water and keep it there.
Fly fishing for marlin is not about making a 90-foot cast. It’s about getting the fly in front of a fired-up fish and keeping it in the zone. Constant false casting can spook a fish off or leave you out of position when it matters. Billfish flies can be bulky and often won’t sink right away when dry. We recommend keeping a bucket full of water, with the fly in it and the line stripped off. When a fish shows up, the waterlogged fly will sink as soon as it hits the water. If a billfish eats your fly, strip set until you feel the weight, and then lift the rod. Never trout set!
Typical billfish flies are tied on tubes to disengage the hook from the fly when a fish eats it. This gives you a better hookup and limits the chances of a fish becoming bill wrapped. For marlin catch and release, this is especially important. Bill wrapping a fish can seal their mouth shut, causing them to drown from a lack of oxygen. The most common colors for billfish flies are blue, pink, and white. The pink/white color combo is especially effective in Costa Rica, where squid are abundant.
Hold On!
You’ve put in the time, made the cast, and hooked your first billfish on the fly. Now it’s time to hold on and dig in for the fight ahead. Marlin, especially, are notorious fighters and have been known to fight to the death. During the initial runs, keep your drag fairly loose. Proper billfish leaders have a light class tippet, or break tippet. As fish run off and dive down, too much drag can pop this section, leaving you fishless. Later on in the fight, as the fish tires and comes closer to the boat, you can tighten up the drag.
Final Thoughts
Catching a billfish on the fly is not for the faint of heart. The persistence it takes to raise fish behind your boat, hook one, and fight them for sometimes hours is back-breaking work. Add to that doing it all on the fly, and there’s a chance you’ll lose more than you catch. Nonetheless, in the world of big game fly fishing, there is no greater accomplishment. A billfish on the fly is a lifetime achievement.
Last Updated on August 26, 2025 by Max Inchausti
