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  • Fly Fishing for Machaca: 5 Tips to Help You Catch This Piranha Relative
  • Post author
    Jesse Males
  • float fishingfly fishingfly fishing tipsfly fishing travelmachacapopper fishing

Fly Fishing for Machaca: 5 Tips to Help You Catch This Piranha Relative

The Machaca Is One of the Baddest Freshwater Fish in Costa Rica, Hands Down.

When I first started talking to my friends back in Florida about how awesome catching machaca on a fly was, most of them had no clue what I was talking about. So let me give you the rundown on this fish species before I get into some tips on catching machaca on the fly.

The machaca is a relative to the piranha and lives in the free-flowing, low elevation jungle rivers. They spend most of their time eating a local fruit called a chilamate. This fruit falls from the trees into the river and machaca tear it up. But these hungry dudes don’t stop there. They eat baitfish, insects, flowers, and leaves, so they pretty much eat everything. Their obsession with feeding on the surface makes them the perfect target for fly anglers.

The size of these fish vary greatly depending on a number of different factors such as fishing pressure, elevation, food sources, and fish populations in each river system. The average fish on a trip is in the 1-3 pound range with shots at 4-5 pound fish being very common.

As a relative to the piranha these fish boast some pretty gnarly headgear that will quickly cut heavy fluorocarbon or even wire if it gets between the teeth for any length of time. 

Machaca hit hard, pull like crazy, and jump like a baby tarpon once hooked. These are the characteristics that made me fall in love with these fish right off the bat.

Now that you know what these fish are all about, lets get into some tips that will help you be successful during your trip.

1. When In Doubt Choose a Bigger Rod.

While machaca aren’t the biggest fish you will find in these rivers, they certainly fight like they are. Machaca spend most of their time cruising in quick rapids or cuts where they feel safe. They are stout fish that quickly run towards cover when hooked.

If you decide to fish with anything less than an 8wt, then you run the risk losing a bigger fish as he runs back into his hiding place. So, do yourself a favor and keep that 8wt out. Trust me. You’re gonna need it!

2. Shooting Heads Are King

After a few trips trying to target machaca on the fly, it became clear that ordinary fishing techniques wouldn’t get the job done on this toothy critter.

We discovered that slamming the fly on the water as hard as possible to mimic a falling chilamate is the best way to get their attention and generate a strike. Using a large shooting head will allow you to get the momentum you need to slam that fly down on the surface as hard as possible.

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When making around 1500-2000 short casts each day, you will want to be sure to let the rod and line do as much work as possible.

3. Choose the Right Fly

Figuring out that machaca are attracted to noise on the surface was the easy part. The hard part was figuring out how to hook them.

Due to the machaca’s piranha type feeding habits, they often strike at the fly and don’t exactly inhale the entire thing at once. This caused some seriously bad hookup ratios at first.

Finally, I began to modify the the Surface Seducer Double Barrel popper flies I had been tying by putting a trailer hook out the back. This was the little something extra that we had been looking for and our hookup ratio doubled, if not tripled. Needless to say this was good news for us!

Something about the way the tail sinks down a bit while the fly is stationary and wiggles when it is popped drives these fish crazy.

I have fished these modified Double Barrel poppers all over the jungle and have found them to be extremely effective not only on machaca, but also on guapote (rainbow bass) and on mojarra as well.

While I wouldn’t recommend fishing the Double Barrel poppers with trailer hooks for every species, it certainly is the perfect fly for machaca here in Costa Rica. It is now a staple in my box during my guided trips and I literally never hit the river without it!

4. Nobody Catches Them All

When machaca fishing, you often have days where you get hundreds of hits on your fly, but you may only hook 15-20 of these fish in a day. This hookup ratio can be frustrating at first for new anglers at first.

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In most fishing situations if a fish hits the fly he is probably going to get hooked, but that couldn’t be farther from the truth with machaca. So, my advice to you is to understand that this is a numbers game and nobody catches them all.

5. Be Smart and Hire A Guide



While I have been fortunate enough to be able to explore these fish over the past 3 years, it is important to note that the places these fish live are fairly remote and can be quite dangerous for the traveler who thinks he is a DIY master. Costa Rica’s lowland river systems are full of vipers and other critters that can turn a pleasant day trip into a life-threatening situation.

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My advice to anglers looking to target these fish is to be smart and hire a guide. My guiding company 506 Outdoors works with locals who grew up on these rivers and know the water like the back of their hand. They work as whitewater rafting guides when not booked with fishing charters and will ensure you are in the best position on the river to focus on casting and landing fish.

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About Jesse Males:

Jesse Males is a longtime fly fisherman from Central Florida and is the owner-operator of backwaterflyfishing.com, which offers HD fly tying videos as well as photo tutorials. His website also features fishing lifestyle blog posts, and fishing videos of his angler adventures. He is a custom fly tyer at his online fly shop backwaterflies.com and a guide for both freshwater and saltwater fly fishing in Costa Rica through his guiding business 506outdoors.com. You can check him out on Facebook and Instagram @backwaterflyfishing. 

  • Post author
    Jesse Males
  • float fishingfly fishingfly fishing tipsfly fishing travelmachacapopper fishing

Comments on this post (5)

  • Aug 30, 2018

    Thanks for the tip, I fish the Rio San Juan in Nicaragua, I just got a couple of fly rod and will try your tips tomorrow. I am sure I will hook me some machacas.

    — Agustin Llanes

  • Aug 26, 2018

    Hi Kevin,
    Costa Rica offers many variety of salt and fresh water species from Atlantic to the Pacific. Tarpon, Snook, Mojarra, Guapote, Rainbow Trout, Rooster Fish, Snapper, Marlin and more… When fishing the lowland rivers in Costa Rica for Machaca as Jesse discusses in this article, you can also target Guapote (known in English as Rainbow Bass) along with Snook and Tarpon. Costa Rica has two seasons, a wet and a dry… however this can change from one side of a mountain range to another in only an hours drive depending on location and time of year. If you are interested in coming to Costa Rica please drop us a email and we will be happy to assist in finding the best time for your preferred species. Thanks for your interest and tight lines.

    — 506Outdoors

  • Aug 26, 2018

    Hi Bruce,
    Jesse is referring mainly to Brycon guatemalensis, which is primarily distributed on the Atlantic slope of Costa Rica. These are the fish we are targeting on a regular basis. The Brycon costaricensis inhabits the Pacific slope of Costa Rica. Hope this helps :-)

    — mark

  • Aug 25, 2018

    I’m confused. When I look up Machaca on FishBase there are six species under that common name ie Brycon behreae, Brycon costaricensis, Brycon guatemalensis, Cribroheros longimanus, Cribroheros robertsoni & Vieja maculicauda.

    Which one are we talking about?

    — Bruce Mahony

  • Aug 24, 2018

    Are there other species to target here and when is the best time to book a trip?

    — kevin leggitt

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