Pacu Identification Guide
Recognize a pacu by its large, deep, piranha-like body paired with a blunt snout and flat, molar-like teeth.
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Key identification features
- Large, deep-bodied, laterally compressed fish that can exceed 24 inches (60 cm) in some species
- Blunt, rounded snout and a straight jawline, lacking a piranha's underbite
- Flat, square, molar-like teeth visible when the mouth is open, built for crushing rather than shearing
- Coloring ranges from silvery-gray to dark olive or black, often with orange to reddish tinting on the belly and fins in some species
- Small adipose fin present, along with a long-based anal fin
Common look-alikes
- Piranha: similar overall silhouette but has a protruding lower jaw and sharp, interlocking triangular teeth rather than the pacu's flat crushing teeth.
- Silver dollar: a much smaller-bodied relative with a lighter, coin-like build compared to the pacu's heavy, robust frame at maturity.
- Related pacu species: often distinguished mainly by belly coloration, orange-red in some, uniformly dark or black in others.
Where you'll see one
Native to major river systems of the Amazon and Orinoco basins in South America, inhabiting flooded forests, main river channels, and large tributaries.
Frequently asked questions
How do I tell a pacu from a piranha at a glance?
Look at the jaw and teeth: pacus have a blunt snout with flat, square teeth, while piranhas have a protruding lower jaw with sharp triangular teeth.
What body trait signals a mature pacu rather than a silver dollar?
A much larger, heavier, deep-bodied frame, since pacus can grow many times the size of silver dollars.