An invasive fish, known in some parts of the world as "The Ball Cutter" due to its alleged appetite for human testicles, has been found in Illinois' Lake Lou Yaeger, reports the Huffington Post.


Residents who frequent the lake have been on guard ever since a local fishermen caught one specimen in June. Originally believed to be a piranha, officials with the Illinois Department of Natural Resources later identified the fish as a pacu-- an Amazonian species related to the piranha. Unlike the piranha, though, which is known for its flesh-cutting serrated incisors, the pacu has blunt chompers that more closely resemble human teeth. They are also much larger than piranha, growing as large as 55 pounds.


The good news is the pacu's diet is normally vegetarian: nuts, leaves and aquatic vegetation. But in some parts of the world the fish is known to feast on nuts of a different sort. In Papua New Guinea, where the species was introduced in the 1990's to bolster local fisheries, the fish has been blamed for a series of horrifying attacks that left some men castrated.


The pacu's reputation in Papua New Guinea is so fierce that locals have taken to calling it "The Ball Cutter." British fisherman Jeremy Wade, star of Animal Planet's "River Monsters," hunted down the fish on one episode to investigate the locals' claims.


"The locals told me that this thing was like a human in the water, biting at the testicles of fishermen," Wade said, according to the Daily Mail. "When I reeled it in, it had this mouth which was surprisingly human-like, it is almost like they have teeth specially made for crushing."


Wade hypothesized on the show that Papua New Guinea's pacu may be reverting back to piranha-like carnivorous diets due to the lack of plentiful vegetarian options in those waters.


There's no reason to believe that the pacu discovered in Lake Lou Yaeger is of the ball-chomping variety, but that hasn't consoled some Illinois swimmers.


"I just got told about it and I am freaked," said mother-of-four Deanne Kirkwood, to KDSK in Illinois. "And now, I am not so sure I want to go in."


Officials say that the waters are safe, though, and that if any more pacu survive in the lake, they aren't likely to survive for long. Since the fish is a tropical species, it won't be able to survive an Illinois winter when temperatures plummet.


The pacu that was caught in the lake was likely a former aquarium fish that got dumped by its owner. Anyone caught dumping non-native aquarium fish into the lake could face criminal charges.