Pacú
Pacú (Piaractus mesopotamicus) is a native of the Paraná-Paraguay river system and one of northern Argentina's most distinctive freshwater targets.
Fish can push past 30 lbs, but what draws fly anglers is the sight-fishing: during summer, pacú move under overhanging trees to eat falling fruit and seeds, creating surface-feeding scenarios that are as demanding and rewarding as anything in freshwater.
Scientific Name: Piaractus mesopotamicus
Also known as Pacú, pirapitinga, Paraná River pacu, small-scaled pacu
- Deep, laterally compressed body — almost disc-shaped — with dark grey to silver sides, white belly, and a distinctive yellow breast.
- Blunt, human-like teeth built for crushing seeds and nuts, not tearing flesh — the clearest visual difference from piranha relatives.
- Typical fish run 10–20 lbs; specimens over 30 lbs are possible in the Paraná system, with a maximum published weight around 44 lbs.
- Serrated keel along the belly — a family trait shared with piranhas — and small scales relative to body size.
What to know
Habitat Distribution
- Native to the Paraguay-Paraná river basin; in Argentina, the core range covers the Mesopotamia region and the upper Paraná drainage, including the Chaco lowlands.
- During high water, adults move into flooded forests and riparian margins to feed under fruit-bearing trees — this is when they become accessible to anglers.
- Also farmed in the rice paddies of the upper Paraná region near Corrientes, where aquaculture operations have grown significantly.
- Classified as Near Threatened (IUCN, 2020), reflecting pressure on wild populations across its South American range.
Key Locations
- Upper Paraná River — the heart of pacú country in Argentina; lodges near Corrientes and the Mesopotamia region target them during summer.
- Corrientes province — the confluence zone of the Paraná and Paraguay rivers holds strong pacú populations and is a base for guided fishing operations.
- Chaco lowlands along the Paraná drainage — flooded forest margins here are prime habitat during high-water summer months.
- Don Joaquin River Lodge area — emerging destination on the upper Paraná system where pacú are targeted alongside golden dorado.
Specific Spots
- Under overhanging trees and bankside vegetation — pacú station here during summer to intercept seeds and fruit dropping from above; look for the slow, deliberate surface sips.
- Slow, clear pools and eddies off the main current, where fish can hold and inspect food without fighting heavy flow.
- Flooded forest edges during high-water periods, when fish push into the shallows to access riparian food sources.
- Deep holes and undercut banks serve as daytime refuges; fish move shallower to feed during low-light periods and when fruit is actively falling.
Pacú FAQ
Answers from onWater's species guide.
What are the best lures and bait for Pacú?
Fruit and seeds threaded on a hook remain a proven fallback when fish are feeding on natural forage and won't take artificials, guides in the Paraná system have used this for decades.
What flies work for Pacú?
Round foam or closed-cell plastic "fruit flies", roughly grape-sized, green or yellow, are the go-to during a seed fall; the audible "bloop" on entry is as important as the visual profile.
When is the best time to fish for Pacú?
Summer (December–March) is the prime window, warm water pushes pacú into the shallows and under fruiting trees, making them visible and catchable. High-water periods during the austral summer open up flooded forest habitat and trigger the most active surface feeding.
How do you catch Pacú?
Most anglers in Argentina target pacú by sight-fishing from a boat or the bank, drifting or casting fruit-imitation flies and lures to fish spotted feeding under overhanging trees. Guides pole or hold position upstream of feeding fish, then present the fly so it lands with a natural splash in the fish's window.
What do Pacú eat?
Primarily seeds, nuts, and fruit that fall from streamside trees, during the summer "seed hatch," pacú feed selectively on round, falling objects and will take imitations that match the size, shape, and entry splash of real fruit.
See it in the app
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