Mark Bowler / Red bellied piranha (Serrasalmus / Pygocentrus nattereri) shoal, Amazon, South America

Peter Scoones / Red bellied piranha (Serrasalmus / Pygocentrus nattereri) pantanal wetlands, Brazil. photographed during making of BBC Planet Earth series 2005

Claus Meyer / Blacktail Piranha (Pygocentrus piraya) underwater portrait, Amazon, Brazil

Konrad Wothe / Blacktail Piranha (Pygocentrus piraya) on hook showing sharp teeth, Pantanal, Brazil

Emanuele Biggi / Animal body parts including snakes and pirhanas for sale at Belen market in Iquitos, Peru. July 2014

Franco Banfi / Red-bellied piranha (Pygocentrus nattereri), on a secondary river from the Paraguay River, Pantanal, Brazil

Franco Banfi / Red-bellied piranha (Pygocentrus nattereri), on a secondary river from the Paraguay River, Pantanal, Brazil

Franco Banfi / Red-bellied piranha (Pygocentrus nattereri ), at night, in tributary of Paraguay River, Pantanal, Brazil

Franco Banfi / Red-bellied piranha (Pygocentrus nattereri ), in tributary at night, Paraguay River, Pantanal, Brazil

Franco Banfi / Yellow king piranha (Pygocentrus natteri), Paraguay River, Pantanal, Brazil

Sylvain Cordier / Redeye Piranha ( Serrasalmus rhombeus / niger ) out of water, close up of teeth, Rio Negro, Amazonas, Brazil.

Sylvain Cordier / Red-bellied piranha or red piranha (Pygocentrus nattereri) out of water, close up of teeth, Rio Negro, Amazonas, Brazil.