Geographical Distribution: Amazon, Araguaia-Tocantins, São Francisco and Prata basins, and weirs of the Northeast (where they were introduced).

Description: Fish with scales. There are many species of piranha, and the body shape and color vary by species. In general, the body shape is oval, the jaw is protruding and the teeth are sharp. The red-bellied piranha has the bluntest snout of this group, with stronger jaw and sharper teeth. It reaches about 12 in of length. The redeye piranha reaches 16 in of length and is the largest piranha in the Amazon.

Ecology: Piranhas belong to a very diverse group of fishes, and the greatest diversity can be found in the Amazon, with at least 20 species. The red-bellied piranha is the most common species. It can be found in lakes and ponds of muddy water and lives in shoals of 12 or more than 100 individuals. Black piranha can be found in rivers of black and clear waters and the individuals are solitary. In some regions, piranhas are appreciated as food, mainly to make the famous piranha broth, considered an aphrodisiac.