Juan Gallo of Petaluma, California, was fishing in a local pond last weekend when he felt a bite and reeled in a fish. Before he could examine his catch, it cut through his line and fell to the ground. That's when he noticed something unusual.
"It landed on the dirt and you could tell it wasn't anything we had seen before," the fisherman told The Press Democrat.
Gallo would later learn that he had reeled in a pacu, an omnivorous fish native to the Amazon river basin in South America and notable for its uncanny mouth of human-like teeth. The species, a close cousin of the piranha, has been turning up in rivers and ponds all across the U.S. due to negligent aquarium owners. The fish are popular in pet stores as juveniles, but can outgrow most home fish tanks after swelling to 10 to 12 inches long as adults.
The pacu has made headlines in recent years after being caught in New Jersey, Washington state, Illinois, Paris, Scandinavia and Papua New Guinea. There's even a captive black pacu in New York City, named Buttkiss, that many believe may be the oldest fish in the five boroughs. Since it's considered invasive in many states, fishermen are encouraged not to release their catch back into the water. Michigan doesn't consider the fish invasive, but the state's Department of Natural Resources did issue a statement asking people to stop releasing the fish into the state's lakes.
don't try this with a pacu fish! pic.twitter.com/aJWc2h4zT4— Lovecraft Raveneve (@lovecraft_raven) May 23, 2016
Back to the pacu's beautiful, eerie, humanesque teeth. The pacu uses them to grind down food, mostly tree nuts that fall into the waters of its native habitat.
"The thing about the Amazon is they're normally vegetarians," biologist Jeremy Wade told Esquire. "If there's plenty of their normal diet around, then they're gonna be happy with that. It eats nuts and seeds that fall from the trees. They have got very powerful jaws and teeth, because some of these nuts are quite hard to crack."
In 2013, the fish created something of a panic after it was mistakenly declared they had a penchant for biting at men's testicles. Wade said he doesn't believe there's any reason for fisherman to be concerned, but maybe don't swim naked in general.
"Yes, there is a chance that someone's little Benjamin there could get bitten by one of these things, but the likelihood is minimal I think," he quipped. "If you want piece of mind just cover yourself up and I think you'll be all right."
Get a closer look at a pacu's teeth in this video:
Editor's note: This story was originally published in June 2016 and has been updated with new information.