GENTLEMEN, PREPARE YOUR wince muscles.

News has reached us that the first European sea sighting of the testicle-eating pacu fish has been reported off the coast of Sweden.

According to the Huffington Post and The Telegraph there have been incidents recorded of the fish attacking mens’ balls.

A specimen was caught by fishermen off the southern coast of Sweden last week.

The pacu is a relative of the piranha and can grow to three feet in length.

Last year one of the fish bit an 18-month-old toddler on the finger at Edinburgh Butterfly and Insect World

According to James Barnes, managing director of the Edinburgh attraction the pacu does eat meat, although it prefers a vegetarian diet.

Pacus will eat anything, even children’s wiggling fingers.

And testicles, it would seem.

According to Swedish newspaper The Local, men have been warned to keep their trunks on when swimming in the sea at Sweden’s Øresund Sound.

A fish expert told the paper that “human testicles are a natural target” for the pacu, which normally feasts on other small fish, fruit and…. yes, you guessed it… nuts.

Denmark’s Natural History Museum is investigating whether this was a one-off catch or if there is the possibility of more pacus turning up outside their native South American habitats.

There are theories that the fish may have escaped from a nearby aquarium, or may have been dumped as an unwanted pet. A pacu was previously caught in the Odra River in Poland in 2002.

According to the museum mens’ testicles are often mistaken for items in the fish’s normal diet, and that the pacus’ penchant for nuts has had fatal consequences for several fishermen in South America.