An exotic pacu has been caught in Sweden’s Oresund Sound, and it’s cause for serious alarm–especially among human males who like to swim there. Pacus, which are native to South America, are related to piranhas, which have sharper teeth and are notorious for how quickly then can remove flesh from the bones of their prey. But pacus, which possess teeth that are almost molar-like and are designed for crushing nuts and fruit, boast a reputation for attacking the most sensitive area on the male human body. Thus, the Natural History Museum of Denmark has issued a warning: “Keep your swimwear on if you’re in bathing in the Sound these days.” The Local, an English-language Swedish newspaper, quotes museum biologist Henrik Carl as saying, “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.” Carl acknowledged that such instances are extremely rare, and that he was having “a bit of fun” in discussing this discovery. But such an ominous warning is bound to at least temporarily eliminate skinny-dipping in the Sound. Meanwhile, the presence of a pacu is as mysterious as it is troubling. More than likely, someone who had kept the tropical fish in a home aquarium released it into the Sound. People are asked to be on the lookout, while also guarding their private parts. “They are almost identical to the piranha, you couldn’t even tell from the outside,” Carl said of the fearsome pacus. “It’s just that they have different teeth. Flatter and stronger, perfect for crushing.” To be sure, if the pacu were a shark, it would warrant a feature on “Shark Week.” And Carl is not unlike those “Shark Week” experts who downplay the danger without really downplaying the danger. While he confessed that “there’s nothing to worry about” and that Swedish swimmers are more likely to drown than being bitten in a sensitive area by a pacu, he did not entirely dismiss the danger. “It could become a problem some time in the future if it’s not the only one,” he said. “This one was the first, but who knows, it’s probably not the last.”