Piranhas belong to the family Characidae and are related to herbivorous species like the Pacu. Piranha can be found in the Amazon and Orinoco river basins, the Guianas and Paraguay-Paraná and São Francisco river systems. Locally they are called Perai. The most famous of the perai are the red-bellied perai (Pygocentrusnatterei) and the black perai (Serrasalmusrhombeus).
Worldwide perai are known for their sharp teeth and voracious appetites. Scientists are still debating which species should be officially included in the Piranha group. While the actual number is unknown it is estimated that there are some 30-60 species in the group. Traditionally, true Piranhas were limited