Pacu - The Testicle Crushing Fish Found in Denmark River

Pacu, a relative of the dreaded piranha has been found swimming in the Danish/Swedish strait of Oresund. Experts at Natural History Museum of Denmark have warned men from swimming naked in the river as the fish is capable of ripping testicles with its sharp teeth.

"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 Peter Rask Møller of the National History Museum of Denmark, University of Copenhagen.

The fish, also called "the ball cutter," can grow up to 55 pounds in size and uses its enormous teeth to crush nuts and small invertebrates. Other reports claimed that the fish species had earlier escaped to Papua New Guinea where it confused nuts with men's private parts.

In 2012, the dangerous fish species was found in Lake Lou Yaeger in Illinois.

In Denmark, the fish was first caught by Einar Lindgreen on August 4. Closer examination of the fish by experts at the Museum confirmed that it was a pacu, a cousin of the infamous South American fish- piranha.

Pacu is native to Amazon and is an invasive species in the U.S. and Asia. Researchers aren't sure how it travelled to Scandinavia. One probable explanation is that it came from The Blue Planet - Denmark's Aquarium- which is located near the river where the fish was found.

"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 Lars Skou Olsen from The Blue Planet, according to a news release.