The word "piranha" is a hybrid term that has its origin in Tupi-guarani language may have originated in the composition of the words 'pirá', meaning 'fish' + 'ranha', meaning 'tooth'. Or - even, it can be originated 'pirá' ('fish') + 'Anha' ('cutter').
It is a fish very voracious predator gifted with very strong jaws. Most piranhas are fast, but usually attack when they are encouraged to do so. Among the numerous species of piranhas, some are cannibals - others, not, but all have aggressive behaviors. Piranhas are close relatives of Pacus and are often confused with them when still small.
On a Friday, July 26 (2013), a visitor of the State of Sao Paulo, the young Vitor Rodrigues Baptista, 15 years - was attacked during a walk in the Lagoon. The victim had to be hospitalized.
The attacks in the Lagoa de Catu are been happening since 2009 (even before) and has resulted in significant damage to local tourism.
There some years, government actions have tried to combat superpopulation of piranhas which presence isn't natural in the environment.
The action of combat to the invasors includes the introduction of a natural predator of piranhas: the tilapias. However, this providence, in these almost four years, don't produced the effect desired. The population of piranhas remains constant and growing.
The Secretary of State for Fisheries and Aquaculture of Ceará, Ricardo Campos, explained that the attacks are occurring due to an imbalance in the food chain.
The pirambeba is not native from that place and came to the pond after a flooding. The pirambeba is native of Ceara, but originally they live in the waters of the Lima Campos reservoir (distant 400 km from Aquiraz).
In 1992, with the construction of the Canal do Trabalhador (a channel), which function is to conduce the water from the Jaguaribe river to supply the city of Fortaleza - new migration routes were created allowing the invasion of piranhas in watersheds that never before harbored this species.