Piranha teeth are often used as tools themselves (such as for carving wood or cutting hair) or to modify other tools (such as sharpening of
darts). This practice has been documented among several South American tribes including the
Camayura and
Shavante in
Brazil and the
Pacahuara in
Bolivia. Piranhas are also popular as food, being both eaten as a subsistence catch by fishers and sold at market. However, they are often considered a nuisance by fishers because they steal bait, eat catches, damage fishing gear, and may bite when accidentally caught. The most common aquarium piranha is
Pygocentrus nattereri, the
red-bellied piranha. Piranhas can be bought fully grown or as young, often no larger than a thumbnail. It is important to keep
Pygocentrus piranhas alone or in groups of four or more, not in pairs, since aggression among them is common, not allowing the weaker fish to survive, and is distributed more widely when kept in larger groups. It is not uncommon to find individual piranhas with one eye missing due to a previous attack.
Attacks Although often described as extremely dangerous in the media, piranhas typically do not represent a serious risk to humans. However, attacks have occurred, especially when the piranhas are in a stressed situation such as the dense groups that may occur when the water is lower during the dry season and food is relatively scarce. Swimming near fishermen may increase the risk of attacks due to the commotion caused by struggling fish and the presence of
bait in the water. and beaches in such areas are sometimes protected by a barrier. Most piranha attacks on humans only result in minor injuries, typically to the
feet or hands, but they are occasionally more serious and very rarely can be fatal. In the state of
São Paulo, a series of attacks in 2009 in the
Tietê River resulted in minor injuries to 15 people. In 2011, another series of attacks at
José de Freitas in the Brazilian state of
Piauí resulted in 100 people being treated for bites to their toes or heels. On 25 December 2013, more than 70 bathers were attacked at
Rosario in Argentina, causing injuries to their hands or feet. Whereas reports of fatal attacks on humans are rare, piranhas will readily feed on bodies of people that already have died, such as drowning victims. In 2011, piranhas were blamed by a local police official for the death of a drunk 18-year-old who jumped into the Rosario del Yata, Bolivia. In 2012, a man from
Manacapuru, Brazil told journalists that his neighbors' five-year-old daughter, who could not swim, was attacked and killed by a shoal of
P. nattereri after entering the water from a floating dock. In January 2015, a six-year-old girl was found dead with signs of piranha bites on part of her body after her family canoe capsized during a vacation in Monte Alegre, Brazil. Family members suspected she had died of drowning prior to her body receiving the piranha bites. ==Reputation==