Skinny dippers rejoice: it turns out there most probably aren’t shoals of testicle-chomping fish off the coast of Sweden.
The find prompted a museum in neighbouring Denmark to issue the knee-crossing warning: "Keep your swimwear on if you're bathing in the Sound these days - maybe there are more out there!"
The pacu fish (pictured) is a relative of the piranha
The words of caution came amid rumours the fish has a penchant for feasting on human scrotums, leading to it’s eye-watering nickname “the ball cutter”.
But following a media furore which caused the story to go viral, Professor Peter Rask Moller of the Copenhagen Museum of Natural History has back-pedalled somewhat on the threat to male Swedish swimmers.
“We did say that we recommend men to keep their swimsuits tied up until we know if there are more pacus out there in our waters,” he wrote in an email to CNN.
“Of course, this is half a joke since it is very unlikely that you would actually meet one and that it would bite you.
“It’s up to people themselves how careful they want to be. I’ll keep my shorts on though.”
That the freshwater fish, which hails from the Amazon was found in European salt waters at all, suggests it was a pet which had been recently released from a home aquarium.
Lars Skou Olsen, the curator of Copenhagen’s Blue Planet Aquarium, reiterated to the National Geographic that swimmers need not be concerned.
Pacu fish can grow up to 90cm in length and weigh up to 25kg. It primarily feeds on nuts, aquatic vegetation and snails.
"The pacu is not normally dangerous to people but it has quite a serious bite, there have been incidents in other countries, such as Papua New Guinea where some men have had their testicles bitten off," Henrik Carl, a fish expert at the Danish museum, told The Local.
Further stirring the pot, he added: "They bite because they're hungry, and testicles sit nicely in their mouth. And its mouth is not so big, so of course it normally eats nuts, fruit, and small fish, but human testicles are just a natural target. It's not normal to get your testicles bitten off, of course, but it can happen, especially now in Sweden."
In further incidents of pacus turning up unexpectedly, last year one was discovered in Lake Lou Yaeger in Illinois, KSDK reported.
In 2011 British fisherman Jeremy Wade travelled to Papa New Guinea to catch his own "ball-cutter" after hearing one had castrated two fishermen who had subsequently bled to death.
He told The Metro: "When I reeled it in, it had this mouth which was surprisingly human-like, it is almost like they have teeth specially made for crushing."