Piranha

The fish whose reputation is scarier than it is

The piranha is a sharp-toothed little fish from the Amazon River. In films they eat a person in a minute — but that's not true! Piranhas mostly eat dead fish, insects and even fruit. Their teeth are razor-sharp — local people used them to make scissors. Piranhas swim in groups, but not to hunt — to protect themselves from bigger fish.

The red-bellied piranha (Pygocentrus nattereri) is the most famous piranha of the Amazon and Paraná basins (30 cm, 3 kg). Its interlocking triangular teeth give one of the strongest bites among fish for its weight — 320 newtons. It is actually omnivorous: carrion, insects, seeds, fruit, other fishes' fins. Shoaling is for defence against predators (dolphins, caimans); when alarmed it makes 'barking' sounds. Attacks on humans are rare and almost never fatal — mostly in droughts when water is low. In 1913 Theodore Roosevelt described a staged show with starved piranhas in his book — the legend began there. There are 30–60 species; some (pacu) eat only plants.

Fun facts

• The scary piranha legend began with a 'show' staged for President Roosevelt in 1913.
• Piranhas eat fruit too — some species are entirely vegetarian.
• Local people made scissors and knives from piranha jaws.