Where are piranha found in the world exactly?

Piranhas (Serrasalmids) are found in South America in particular Brazil, Colombia, Venezuela, Bolivia, Ecuador, French Guiana, Guyana, Paraguay, Peru, and various river systems.

Large and aggressive piranha native to the Sao Francisco River basin in Brazil, the fish Pygocentrus piraya is also known as the piraya piranha or San Francisco piranha. Pygocentrus piraya piranha are found in Brazil (Minas Gerais, Alagoas, Bahia, Pernambuco, Sergipe).

The Serrasalmid species Pristobrycon careospinus piranha is found only in Venezuela, Colombia (Colombia (mainland)); Venezuela, Bolivarian Republic of (Venezuela (mainland)).

Serrasalmus humeralis often reaches a length of 20 cm. It is a member of the family of fin-eating piranhas, which, if one want to preserve intact specimens, should be kept in an aquarium for an extended period of time, preferably in separate tanks. Serrasalmus humeralis piranha is found in Bolivia, Plurinational States of; Brazil; Colombia (Colombia (mainland)); Ecuador (Ecuador (mainland)); French Guiana; Guyana; Paraguay; Peru; and Suriname.

Serrasalmidae (serrasalmids) are a newly recognized family of characiform fishes. More than 90 different kinds of animals and plants are known. The serrated keel that runs along the belly of these fish is the inspiration for the name, which translates to "serrated salmon family." Serrasalmidae are commonly referred to as pacu, piranha, and silver dollar, all of which are common names for these fish. Names like "buck teeth" or "snake mouth" typically refer to distinct dental features or eating habits.

References

Serrasalmidae
Pygocentrus piraya locations
Pristobrycon careospinus locations
Serrasalmus humeralis locations