You're looking at a pacu. It's related to the piranha, is native to South America, and has been nicknamed the "ball cutter." You can probably guess why, but if you're still not sure, here's Henrik Carl, a fish expert at the Natural History Museum of Denmark to explain the pacu's particular "gimmick":
"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. They bite because they're hungry, and testicles sit nicely in their mouth."
Despite being associated with South America, a pacu was recently discovered in the Oresund Sound between Denmark and Sweden. Which means this crotch-chomping creature of the deep is on the move...
