Machaca – Flower Eater of the Costa Rican Jungle


A distant relative to the Amazon’s piranha, Brycon costaricensis or the machaca, is an interesting and highly enjoyable fish to pursue on fly. The fish inhabit lakes and fast moving rivers in lowland drainages of Costa Rica. At first glance, the row of ferocious teeth lining the machaca’s grin speaks of a savage predator of smaller fish, and yet this is not entirely true. Juvenile machaca do eat aquatic and terrestrial insects, but as the fish grow to adulthood their diets turn largely vegetarian, consuming any fruit,  flowers, and leaves that fall into the waters they patrol.

Slapping poppers and even flower and fruit flies onto the surface of the river to mimic the falling edibles entices aggressive topwater takes, and on some windy days when the trees crowning the river are ripe sudden gusts shower down fruit or flower pedals much to the joy of many surface feeding machaca. Its not often that one can speak of the fantastic flower hatch that happened throughout the course of a fly fishing day while floating down a remote jungle river!



Machaca are extremely aggressive, and throwing poppers behind overhanging branches along the bank often triggers several fish to attack from below. Once hooked, the fish are as aerial as mini tarpon and as strong as any other river fish, doggedly pulling into roots and snags in an effort to break free. Its great sport, and in our opinion one of the most underestimated fish for fly out there. If South America’s pacu is the “river permit” then its only appropriate that the machaca is the “river bonefish”.

The fishing is from a whitewater raft or river panga (depending on the river) operated driftboat style and suitable for 2 anglers. We recommend 5-7 weight rods to help reduce arm fatigue from throwing large poppers throughout the day. Most machaca weigh around 2-4 lbs, but there are many larger fish in the river and you’ll be happy to have a little extra rod if you connect with one of these powerful 5+ lbers. Leaders can be fished to 10 or 12 lbs. with a small piece of 20 lb. fluorocarbon acting as a bite tippet. Flies generally match whats in season, and we recommend panfish and largemouth poppers in green, yellow, orange, and red for the various types of fruiting and flowering trees with a few extras in black and white to mimic the machaca’s favorite treat – bird poop. To spice things up even more, the rivers are also inhabited with rainbow bass, or guapote lagunero, and Atlantic snook, so throw a few small streamers in your bag and you should be good to go. Flies specifically tied to suit our rivers are for sale should you want to take the guess work out of the experience.



Machaca fishing can take place in several standout rivers around the country, and can be treated as a one-day trip or extension to any of our other Costa Rica programs. Let us help fit a day on the river into your trip to Costa Rica!

Ever dreamed of a serious tropical camping adventure? Depending on the season, we also offer multi-day exploratory adventures on some of the country’s largest rivers, floating together with a support vessel and camping on a remote river bank under the stars for a fly fishing adventure of truly epic proportions.