Angler Charles Harker was fishing the White River near Muncie, Illinois, when he caught what first appeared to be a large bluegill--until he saw its teeth.

The fish is believed to be a 12-inch piranha, the highly carnivorous fish native to the Amazon River.

The fish was most likely released illegally into the river after it outgrew someone's home aquarium. Biologists say piranhas cannot survive the harsh Illinois winters, so there is little chance that a breeding population of the fish has taken hold.