Arapaima gigas
The pirarucu is the largest scaled freshwater fish in the world and the centerpiece of Amazon sport fishing in Brazil. Native to the Amazon Basin, it draws anglers from around the globe to waters like the Mamirauá Reserve and lakes near Manaus.
Its habit of surfacing to breathe air every 20 minutes or so makes it uniquely visible — and uniquely stalkable — in a way almost no other freshwater fish is.
Scientific Name: Arapaima gigas
Also known as Pirarucu, Arapaima
- Long, canoe-shaped body with a copperish-green head, black flanks with a white center, and a deep red tail that intensifies with age — unmistakable at any size.
- Large, heavily armored scales form a natural defense against piranha; the bony, upturned mouth and massive stumpy tail are the most distinctive structural features.
- Typical fish run 7–8 feet and around 200 lbs; the largest confirmed specimens exceed 10 feet and push past 400 lbs, making them the heaviest freshwater fish in South America.
- Juveniles are dark brown overall; red markings on the rear of the body become more prominent as the fish matures.
What to know
Habitat Distribution
- Native to the Amazon River system in Brazil, including the Rio Tocantins basin in central Brazil; also found in the Solimões and Japurá river corridors in the western Amazon.
- Lives in slow-moving rivers, oxbow lakes, flooded forests, and isolated lagoons — anywhere warm, shallow, and often oxygen-poor where its air-breathing ability gives it an edge over other fish.
- The Mamirauá Reserve, roughly 600 km west of Manaus between the Solimões and Japurá rivers, holds the largest wild pirarucu population on Earth and is the primary sport-fishing destination.
- Isolated lake systems just outside Manaus also hold fishable populations, independent of the flooded forest and accessible through much of the season.
Key Locations
- Mamirauá Reserve (western Amazon, between the Solimões and Japurá rivers) — the largest wild pirarucu reserve on Earth, roughly 600 km west of Manaus; home to the Pirarucú fly-fishing operation.
- Isolated lake systems near Manaus — accessible as day trips, these managed fisheries hold active, hungry fish and are the most consistent option for anglers with limited time.
- Central Amazon floodplain lakes — part of the three key fishery regions that account for the majority of Brazil's pirarucu population, particularly productive during the dry-season drawdown.
- Rio Tocantins basin in central Brazil — part of the native range and a secondary fishery region outside the main Amazon floodplain.
Specific Spots
- Shallow lagoons and oxbow lakes during the dry season — lower water concentrates fish and makes surface-breathing fish visible from a distance.
- Near banks and flooded forest edges, where pirarucu surface predictably; watch for the distinctive splash and ripple, then pole into casting range.
- Narrow channels connecting larger lagoons funnel fish movement and create reliable intercept points during the dry season drawdown.
- Mid-lagoon open water when fish are actively cruising — look for the back breaking the surface, mark a landmark on the bank, and cast just beyond the fish before it dives again.
Arapaima gigas FAQ
Answers from onWater's species guide.
What are the best lures and bait for Arapaima gigas?
Large swimbaits and paddle-tail soft plastics (6–10 inches) on heavy jig heads imitate the baitfish that make up the bulk of the pirarucu's diet and are effective in both lake and river settings.
What flies work for Arapaima gigas?
Large baitfish streamers (6–10 inches) on 4/0–6/0 hooks are the primary pattern, Deceiver-style flies and large Clouser Minnows (which imitate baitfish with a weighted, jigging action) are the go-to choices at Mamirauá and in the Manaus lake fisheries.
When is the best time to fish for Arapaima gigas?
August through March is the primary fishing window, covering the dry season and early wet season when water levels are manageable and fish are concentrated.
How do you catch Arapaima gigas?
Most anglers in Brazil pursue pirarucu by sight, poling or drifting quietly through lagoons and watching for the fish to surface and roll, then positioning for a cast before it dives again. Both fly and conventional anglers use this approach, with guides doing the poling and calling the shots on timing and placement.
What do Arapaima gigas eat?
Primarily eats other fish, using a vacuum "gulper" strike, opening the massive mouth to pull in prey. Large baitfish-imitating streamers and big subsurface flies work because they match this feeding mode. Also takes crustaceans, insects, birds, small mammals, and fruits from the surface.
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