The pacu–a type of biting fish–poses a risk for skinnydippers in Scandinavia after a local found a pacu in waters that separate Sweden and Denmark.
The pacu is related to the piranha, is originally from South America, and has large teeth. Authorities warn that these fish can attack men’s testicles.
Amateur fisherman Einar Lindgreen caught the fish in the Oresund Sound earlier this month, according to the National History Museum of Denmark.
“There is however no cause for panic say experts. The fish, though exotic, is a Pacu, not a piranha. None the less they caution male swimmers to protect their privates when swimming in the sound,” the museum wrote in a statement.
Associate Professor and fish expert Peter Rask Moller of the National History Museum of Denmark, University of Copenhagen said the next step will be to determine if the fish that was caught is a “lone wanderer” or if it signals that the fish is becoming “a new invasive species.” Nonetheless, he added, it will be “very exciting. And a bit scary.”
Officials at the museum suggested that men should keep “swimwear on if you’re bathing in the Sound these days – maybe there are more out there.”
“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. He added: “It’s not normal to get your testicles bitten off, of course, but it can happen, especially now in Sweden.”
The fish–which can weigh as much as 40 pounds–normally eat fruits, small fish, and nuts. “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,” Karl said.
In 2011, a pacu was blamed for the death of two men in Papua New Guinea, according to the Daily Mail.
“I had heard of a couple of fishermen in Papua New Guinea who had been castrated by something in the water,” fisherman Jeremy Wade, originally from the U.K., told the Mail.
In 2012, the fish was spotted in Lake Lou Yaeger, Illinois. It seems most likely that the fish were dumped by exotic fish collectors.