Last month, during a visit to Jaycee Park in Cape Coral, Florida, Leah Getts’s son spotted a massive dead fish floating in the Caloosahatchee River. “It was bigger than my 7-year-old, who’s not a small kid,” Getts told NBC2. She shared a photo of the fish on Facebook, and her followers helped identify it as an arapaima—a freshwater species native to the Amazon River.

Arapaima (Arapaima gigas) can’t survive in cold water, so they’re not known to venture near North America regularly. But parts of southeast Florida may now be warm enough to host them, which could pose a threat to the region’s existing wildlife. The predatory fish isn’t a picky eater—it primarily feasts on other fish, but it also eats fruit, insects, birds, and even mammals. And since an arapaima can lay thousands of eggs per year, it wouldn’t take long for it to become a major invasive species.

The Florida Fish and Wildlife Conservation Commission told the Associated Press that there’s “no evidence that arapaima have reproduced in the wild in Florida” yet, but they’re asking people to report any sightings of the fish, which you can do here.

In the meantime, here are five fascinating facts about the aquatic behemoth.

1. The arapaima is one of the largest freshwater fish in the world.

Though the specimen found in Florida’s Caloosahatchee River was only about 5.5 feet long, arapaima can be much larger. Typical ones measure 7 to 8 feet and weigh around 200 pounds, but they’ve also been known to reach nearly 15 feet and tip the scales at around 440 pounds.

2. The arapaima is an air-breathing fish.

The arapaima can stay submerged for roughly 10 to 20 minutes before it needs to surface for air. It breathes not through its gills—which are too small for the job—but by opening its mouth and funneling air into a lung-like gas bladder. According to National Geographic, “the noisy, distinctive gulp it makes sounds like a cough and can be heard from far away.”

3. Arapaima are also known as the pirarucu fish.

The arapaima dwells in several South American countries, so it’s known by more than one name. For Peruvians, it’s paiche. Brazilians call it the pirarucu, from the words for red (urucu) and fish (pira) in the Tupi language.

4. The arapaima boasts impressive body armor.

"Hit me with your best shot."vinhdav/iStock via Getty Images

The arapaima’s scaly coat is basically the fish version of a bulletproof vest, which helps protect them from cold-blooded killers like piranhas. The scales comprise two layers: a hard exterior made of minerals, and a flexible interior made of collagen. Unlike human-made bulletproof vests, however, those aren’t fused together with a third adhesive layer—the two layers of each arapaima scale actually grow together. This makes it ideal for pressure absorption and range of motion, which researchers hope can help inform advances in materials science.

5. The arapaima appeared in Animal Crossing: New Horizons.

Animal Crossing: New Horizons introduced the arapaima to its virtual waters in 2020, along with great white sharks, ribbon eels, and a whole host of other aquatic offerings. Players in the Northern Hemisphere can only find them in rivers from June to September, between the hours of 4 p.m. and 9 a.m. But catching one will earn you a pretty penny—they’re valued at 10,000 bells each, making them one of the most expensive fish in the game.