Swedish men have been warned to keep their swimming trunks on after a South American fish known for attacking testicles was found in the sea. A fisherman in the Oresund Sound between Denmark and Sweden retrieved a 8 inch pacu. The Pacu, which is a relative to the piranha, is typically found in South America. The fish is nicknamed the "ball cutter" for its attacks on male genitalia. The pacu usually eats fruit, small fish and nuts. Henrik Carl, a fish expert at the Danish museum said, "'They bite because they're hungry, and testicles sit nicely in their mouth,"