Which freshwater fish is often called the red-bellied piranha?

Pygocentrus nattereri is the freshwater fish commonly called the red-bellied piranha. Adults typically have a silvery body with an orange-red underside, while their deep, laterally compressed bodies and sharp teeth help them bite pieces from prey and carrion.

The red-bellied piranha is native to tropical South America, including major river systems such as the Amazon, Paraná, and Essequibo basins. It eats fish, insects, crustaceans, plant material, and carrion, so its diet is broader than popular stories often suggest.

Piranhas are not all the same species. Black piranhas and other members of the family Serrasalmidae differ in appearance, range, and feeding habits. The name “red-bellied piranha” specifically identifies Pygocentrus nattereri, rather than every piranha with a reddish underside.