Mylossoma duriventre
The pacu-manteiga is a deep-bodied, laterally compressed serrasalmid that supports small-scale commercial fisheries across Brazil's major river systems.
In Mato Grosso, specialized fishing for Mylossoma targets the Cuiabá River and surrounding floodplain waters. It's a table fish first — valued for its flavor — and a sport fish second, taken incidentally by anglers working floodplain lakes and river channels.
Scientific Name: Mylossoma duriventre
Also known as pacu, pacu-manteiga
- Deep, strongly compressed body — almost disc-shaped in profile — with a silvery flanks and a distinctive black blotch on the opercle (gill cover).
- A row of abdominal spines runs along the belly; the last spine reaches or nearly reaches the anal-fin origin — a key feature separating this species from close relatives like M. aureum.
- Typical adults run to about 25 cm (10 in) and top out near 1 kg (2.2 lb); maturity begins around 17 cm.
- Fewer lateral-line scales and fewer anal-fin rays than the similar M. albiscopum, which occupies the Amazon basin proper.
What to know
Habitat Distribution
- Native to the Río de la Plata basin — the Paraguay, lower Paraná, and lower Uruguai rivers — which includes the Brazilian Pantanal and parts of Mato Grosso do Sul.
- Specimens have also been recorded from the Middle Madeira River Basin in southern Amazonas and from the Vale do Juruá in Acre, though taxonomic boundaries between Mylossoma species in these areas are still being resolved.
- Prefers nutrient-rich, warm floodplain waters; also found in the lower reaches of nutrient-poor rivers during flood season.
- A freshwater migrant — moves entirely within river systems, using flooded forests and lakes during high water, retreating to main channels as water drops.
Key Locations
- Rio Cuiabá, Mato Grosso — specialized Mylossoma fisheries operate throughout this river and its floodplain.
- Middle Madeira River Basin, southern Amazonas — documented in small-scale fisheries and scientific surveys.
- Vale do Juruá, Acre (Cruzeiro do Sul area) — described as abundant and commercially important in recent research.
- Pantanal floodplain (Mato Grosso / Mato Grosso do Sul) — core range of the Paraguay basin population.
Specific Spots
- Flooded forest edges during the high-water season — fish move into the trees to feed on fallen fruit and seeds, so work the timber line.
- Floodplain lakes (lagoas) connected to main channels; fish concentrate here as floodwaters recede and food becomes more predictable.
- Main river channels near submerged structure — root mats, fallen trees — where current breaks create feeding lanes.
- Shallow, vegetated margins in nutrient-rich backwaters, where plant material and invertebrates accumulate.
Mylossoma duriventre FAQ
Answers from onWater's species guide.
What are the best lures and bait for Mylossoma duriventre?
Natural baits dominate: fruit paste, corn, bread dough, and locally available fruits fished on small to medium hooks under a float or on a light bottom rig. Small spinners and spoons can draw strikes when fish are active in open water, but bait fishing is far more consistent given the species' herbivorous diet.
When is the best time to fish for Mylossoma duriventre?
Flood season (roughly November–April in the Pantanal and Amazon catchments), fish disperse into flooded forest and lateral lakes, making them accessible to bank and small-boat anglers working the timber edges.
How do you catch Mylossoma duriventre?
Most fishing for pacu-manteiga in Brazil is done from small boats or the bank, using natural baits fished under a float or on a light bottom rig near flooded forest edges and floodplain lakes. Artisanal fishers time their effort to the flood pulse, when fish are most accessible in lateral waters.
What do Mylossoma duriventre eat?
Primarily herbivorous, feeds on plant material including fruits, seeds, and aquatic vegetation. During flood season, fallen fruits in inundated forest are a major food source; match this with fruit-imitation baits or dough baits made from local fruits.
Where do Mylossoma duriventre live?
Native to the Río de la Plata basin, the Paraguay, lower Paraná, and lower Uruguai rivers, which includes the Brazilian Pantanal and parts of Mato Grosso do Sul.
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