The Mutilator

"Jeremy Wade travels to Papua New Guinea to investigate a spate of bizarre deaths on one of the world's last great unexplored rivers, the Sepik. A creature there is tearing chunks from unsuspecting fishermen and devouring certain male body parts. Jeremy has never fished in this part of the world and knows little of what might be there. Nothing could prepare him for what he discovers."

Synopsis
Deep in the jungles of Papua New Guinea, two separate deaths have attracted the media: two men were found to have bled to death in the Sepik river as a result of a "ball cutter" attacking villagers. Jeremy Wade travels to this unexplored river to uncover the creature responsible for the savage attacks.

While fishing for a possible food source, Wade makes an unusual discovery. A pacu from the Amazon river. These fish are related to the piranha and are from South America, where they use their strange, almost human-like teeth to actually crack hard-shelled nuts and fruits and eat them.

Jeremy makes a terrible discovery about the seemingly-placid red-bellied pacu living in the Sepik. These animals here can actually have a taste for human flesh.