The Telegraph reports that Swedish swimmers are being warned of testicle-munching fish after a South American fish know for chomping down on the family jewels was found in a sound off the country’s southern coast.

“Discovering whether this fish is a lone wanderer or a new invasive species will be very exciting. And a bit scary. It’s the first time this species has been caught in the wild in Scandinavia,” said fish expert Peter Rask Møller of the National History Museum of Denmark in a statement.

The pacu fish, which is a relative of the piranha, is typically found in Amazon region. According to the Natural History Museum of Denmark, the pacu is vegetarian, unlike its carnivorous relative. While able to sever fingers and fishing lines, the pacu’s teeth aren’t as sharp as the piranha’s. So what’s all the big fuss about? According to CNN, pacu fish enjoy crushing nuts with their strong jaws and occasionally have trouble distinguishing between testicles and some delicious nuts.

The museum reports that this particular red-bellied pacu was caught by Einar Lindgreen last Sunday. Lindgreen discovered the testicle-munching fish when he emptied his nets and spotted the pacu among eels and perch. When Lindgreen showed his special catch to his friends, they thought that he had hauled in a piranha from South America. After being sent to the Natural History Museum of Denmark for further study, the experts at the museum quickly determined the fish is actually the pacu fish, not the meat-eating piranha.

How did this fish from the Amazon region make its way to the Danish/Swedish strait of Oresund? According to the museum, the pacu likely found its way to this body of water just like other fish find their way to non-native bodies of water: someone likely dumped the fish in the strait of Oresund. However, there are others that think that pacu fish escaped from Denmark’s Aquarium, The Blue Planet.

“We do exhibit Pacus in our Amazonas exhibition, but ours are a lot larger than the one caught. And even though the distance between our aquariums and Øresund can be measured in meters there are sophisticated filters in place to avoid contamination. So this is not one of our fish,” said The Blue Planet curator Lars Skou Olsen.

Just like the monster goldfish found in Lake Tahoe, which is thought to have been dumped in the lake by aquarium owners, the pacu fish is probably from someone’s aquarium or fish farm.

“Amateur aquarium owners and fish farmers are ‘The usual suspects’ when we meet fish where they do not belong,” said Møller. “It is not unlikely that someone has emptied their fish tank into a nearby stream just before a vacation and that the Pacu then swam out into the brackish waters of Oresund. We don’t know of any commercial farming of Pacus in Europe. But just like the Piranhas the Pacus are quite easy for amateurs to raise.”

In many parts of the world, the pacu fish is now considered an invasive species by wildlife officials.

This is not the first time that a pacu fish has been discovered far from its homeland. The museum notes that an angler caught a pacu near a power plant on the Odra river in Poland in 2002. The pacu fish has also been spotted in the U.S.

According to the Huffington Post, one of the testicle-eating fish was found in Lake Lou Yaeger in Illinois in 2012. Lake superintendent Jim Caldwell took the fish to the Illinois Department of Natural Resources, where it was determined to be a pacu.

Despite its fearsome teeth and enormous size (they can weigh up to 55 pounds), Caldwell was unimpressed by the fish. He told KDSK that pacu fish pose no real danger to humans.

While Caldwell may not be impressed with the pacu fish, there’s a reason that the fish is a known as a testicle eater. The Metro reports that the pacu fish is rumored to have killed two local men in Papua New Guinea by biting off their testicles. Jeremy Wade, star of the TV series “River Monsters,” is credited with catching the testicle-chomping fish.

Møller said the he and his colleagues are still interested in examining the fish.

“In order to be one hundred percent certain of the identification we will now perform a genetic examination, as there are several species of Pacu which are very similar when young. In the aqua culture busines they even produce hybrids between species,” said Møller.

Would you swim in a lake or body of water if a testicle-chomping pacu fish had recently been found in it? Did this fish come from an aquarium, a fish farm or Denmark’s The Blue Planet? Share your thoughts in the comments section.