Piranha

About

Found in the Amazon basin and possibly the Essequibo drainage, Serrasalmus serrulatus belongs to a genus of predatory characins that the English-speaking world lumps under the "piranha" label. Though in South America that name is reserved for Pygocentrus species like the red-bellied piranha. Serrasalmus fish go by different regional names entirely, and the distinction matters because these groups, while related, show clear physical differences in mature specimens. This particular species sits in what researchers call the "humeralis group," a cluster of closely related fish that are notoriously difficult to tell apart. Even experts struggle to separate S. serrulatus from several near-identical congeners, and the taxonomy of the whole genus is overdue for a thorough modern revision. For the aquarium keeper, this animal is strictly a solo act. It will not coexist peacefully with other fish, or even its own kind, and should be the only resident of its tank. That said, the media's monster-fish reputation is overblown. These fish are more skittish than aggressive in captivity, tend to calm down with age, and can live over a decade with proper care. They are best suited to a dedicated enthusiast who understands what they are getting into rather than a community setup.