Pacu
The Pacu fish has a fearsome set of teethNTV Television

A Pacu fish - dubbed the "nutcracker" because it is claimed they bite off fishermen's testicles - has been caught in a lake in southern New Jersey.

Due to its ferocious set of teeth father and son fishermen Ron and Frank Rossi thought they had hooked a piranha out of the man-made lake, reported The Daily Star.

The Pacu – a fish native to Brazil - can grow up to four feet long and weigh up to a whopping 55lbs.

New Jersey's Department of Environmental Protection said in a statement: "Many times, these fish are deposited into lakes by pet owners. These fish do not survive in colder water, so we encourage people not to release it into the wild but to humanely destroy the fish."

The department's Lawrence Hajna moved to calm fishermen's fears, saying: "People confuse them as piranhas a lot, but they have teeth made for grinding instead. They'll eat nuts that drop in the water in the rain forest, hence the urban legend that they eat a certain part of the male anatomy [the testes].

"Just to clarify, they don't eat the male anatomy."

Hanja told ABC News that the fish had probably outgrown its aquarium, so its owner decided to release it into the lake, hoping to give it a roomier home. "It's unusual, but we get a couple reports every year," he said. "The best thing to do is humanely dispose of the fish instead of dumping it in a lake."