London - A fish with a taste for human testicles has been caught in the Seine in Paris.

Among a variety of nicknames, the razor-toothed Pacu is popularly known as The Nutcracker.

The Piranha-like fish – which can weigh up to 25kg – is mainly found in tropical South American waters.

It is known for gliding below male swimmers and taking a nibble out of their most sensitive organs – sometimes allegedly tearing them off and swallowing them whole.

An angler in Paris alerted river police after reeling in a small specimen.

“He sent us an image of the picture through his smart phone and it turned out to be a Pacu,” said a police spokesperson, adding: “It is a fish with a very dangerous bite.” The Pacu, which comes from Brazil, is mostly vegetarian, but for unknown reasons is attracted to male genitalia.

It has been recorded around the world, with unconfirmed reports of fishermen in Papua New Guinea having their genitalia ripped off.

When one was found in Denmark last month, Copenhagen University professor Peter Rask Moller said: “All we suggested was that swimmers keep their pants on until we know if there are more of these fish out in our brackish waters.”

When Pacu turn up in strange places, it is usually because the owner of an exotic aquarium has released them.

Biologist Peter Moyle said: “Pacu are commonly kept in aquaria because they are fairly docile, but look like piranhas.

“They grow quickly in captivity and will outgrow aquaria, so owners release them locally.”

Fortunately, the Seine is too dirty for swimming, and police say chillier weather will soon kill off any remaining Pacu in the French capital. - Daily Mail