serrasalmus nattereri

This species of red belly is also known as the red piranha (Pygocentrus nattereri), is a species of piranha native to South America, found in the Amazon, Paraguay, Paraná and Essequibo basins, as well as in the coastal rivers of northeastern Brazil. This fish is locally abundant in freshwater habitat. They are omnivorous foragers and feed on insects, worms, crustaceans and fish. They are not a migratory species, but travel to seek conditions conducive to spawning and rearing during periods of increased rainfall. Red forks often travel in herds as an aggressive defense, but rarely exhibit group hunting behavior. Acoustic communication is common and sometimes exhibited along with aggressive behaviors. Through media influence, the red-legged piranha has developed a reputation as a ferocious predator, although this is not actually the case. It is a popular aquarium fish.