A strain of pacus is potentially invading the waters of Oresund, the strait that runs between Sweden and Denmark. What is a pacu, you ask? A fish rumored to dine on the exposed testicles of men.
CNN reports that representatives from the Natural History Museum of Denmark have cautioned against swimming nude in Scandinavian waters after a fisherman pulled a red-bellied pacu from the strait on August 4. The fish, which can grow up to a sizable 55 pounds, is typically found in the warmer rivers and streams of the Amazon and Orinoco river basins.
Pacus are cousins to the much more maligned piranha. Unlike that carnivorous creature, the pacu is a vegetarian with a diet that includes, among other things, the nuts of trees. Unfortunately, the fish is not the most discerning when it comes to taking a bite out of a perceived meal.
Rumors of the fish’s penchant for biting the testicles off of unsuspecting men are far and wide, including an account in the British journal Metro concerning a couple of fishermen dying from blood loss after the pacu castrated them in Papua New Guinea. Regardless of the tale’s validity, it is said that human attacks by the fish are extremely rare.
The appearance of the pacu in the Oresund may point to a larger problem if more are discovered, as the fish should not flourish in the colder waters of Scandinavia. They are also an invasive species in this scenario; if left unchecked, they will begin to drive out local species native to the region.
How did the fish end up in and around the strait? Museum employee Peter Rask Moller points to “amateur aquarium owners and fish farmers” as the likely culprits. The fish are sometimes released into the wild by caretakers unaware of the damage they might be doing to a local ecosystem. Pacus, like piranhas, are fish that can be easily raised by most people.
This is not the first time the toothy fish has appeared outside its natural habitat. Pacus have reportedly been spotted in U.S. states including those along the west coast, Wyoming, and Minnesota. The fish was caught just last year in Lake Lou Yaeger in Illinois.
The museum intends to run genetic tests on the pacu caught in the Oresund to learn more about it. Meanwhile, they advise skinny-dippers willing to risk an encounter with the fish to “keep their swimsuits well tied.”