From the Ichthypundit

Toothy piranha more interested in bark than bite

A "piranha" caught in the Warrior River (which I drive over every day) turns out instead to be a paca, a close relative of the piranha but a vegetarian. Once again, someone apparently dumped an aquarium fish into the nearest river. It's tropical and probably couldn't survive here. However:

Wildlife and Freshwater Fisheries officials are particularly concerned about the Southeast Asian snakehead fish. They’re hardy fish and prolific breeders that closely resemble a native species, the bowfin or grinnel.