Invasive South American fish known as the 'vegetarian piranha' found in Tennessee

A Tennessee fisherman's suspicions that he caught something extraordinary were confirmed over the weekend when state officials determined the fish was a South American pacu, a species related to the famously vicious piranha.

One big difference, however: Pacu are vegetarians, the Tennessee Wildlife Resources Agency reported.

"The pacu is commonly called the 'vegetarian piranha.'" the agency said in a Facebook post. "Don't let their teeth freak you out, pacu are vegetarians and don't eat meat.

"Pacu have teeth that look very similar to human teeth. They have two sets of blunt molars that are used for cracking nuts and grinding up plants."

Pacu are not considered harmful to humans, but are an invasive species that can "overrun the waters they occupy," state officials said.

Fisherman Randall Adams caught the pacu recently in Rony Pond, a body of water within the John Tully Wildlife Management Area along the Mississippi River. A photo of the fish was shared by the state on Facebook, showing the dingy colored fish was flat-bodied, with fins on its back and belly.

Pacu grow up to 42 inches in length and can weigh as much as 97 pounds depending on the species, state officials said. They are "delicious" and often served in restaurants in South America, officials added.

"How did it get into Rony Pond? Pacu are suitable for home aquariums, but grow rapidly and can live for 15-25 years. So the odds are the fish outgrew its aquarium, and someone relocated the fish to Rony Pond," state officials wrote on Facebook.

"It's illegal to relocate or stock fish. Illegal stockings are one-way exotic species are introduced to waters and can harm our native fish populations through diseases or harmful viruses."

Investigators suspect the pacu was recently put in the pond, because the species can't survive in winter temperatures below 58 degrees.

This is not the first time a pacu has been caught in southern waters. The Mississippi Department of Wildlife, Fisheries and Parks reported on Facebook that one measuring 15 inches long was caught in Issaquena County's Steel Bayou in 2012.

Angler Maxine Smith of Mayersville told state officials the fish was surprisingly strong. "All of a sudden I hooked a fish that almost snatched me into the water," Smith was quoted saying. "At first, I thought it was a big shad or a buffalo, but then I saw the teeth!"