Usually found only in warm waters of the Amazon River, the Pacu, a relative of the Piranha, can grow up to a length of 90cm and a weight of 25kg.
So it came as a complete surprise when a 21cm Pacu was caught in an eel trap in Oresund Sound off the south coast of Sweden.
Although the Natural History Museum of Denmark is testing the DNA of the fish to confirm that it is in fact a Pacu, they issued a very succinct warning to the public: "Keep your swimwear on if you're bathing in the Sound these days - maybe there are more out there!"
This is absolutely no joke - this species of invasive fish has become infamous for attacking human testicles. In fact, Pacus have reportedly killed fishermen who have bled to death after losing their testicles.
According to fish expert Henrick Carl of the Natural History Museum, the freshwater fish bite "because they're hungry, and testicles sit nicely in their mouth". He continued by saying to local news media, "They are almost identical to the piranha... It's just that they have different teeth. Flatter and stronger, perfect for crushing."
"It normally eats nuts, fruit, and small fish, but human testicles are just a natural target. It's not normal to get your testicles bitten off, of course, but it can happen ...," said Mr Carl.
BALL-CUTTER INDEED!! WTH??