Before I saw a video on YouTube, I had never seen anyone catch a pacu. The pacu is a fish native to the Amazon region in South America. Related to the piranha but not a maneater like its cousin, the pacu can grow to 80 pounds. It’s also a hard fighter.

The fisherman in the video spots the pacu while pursuing another species. He grabs his bass rod and presents a white, soft-plastic jig to the fish. It pays off. The pacu grabs the lure and takes off on a tear.

In the video, on light tackle with eight-pound test line, the angler must take his time fighting the pacu, which looks to be close to six pounds. The roundish, dull gray fish makes a dozen or so runs before the angler finally guides it into the landing net. He holds up his quarry for the camera, smiling proudly after winning the confrontation with his line still intact.

The astonishing thing about the video is that the angler is not fishing some backwater lagoon of the Amazon basin. He’s fishing a backyard Florida lake in a suburb of Miami. Fishing for exotic, non-native species has become so common in the region that southern Florida has been dubbed “Little South America.”

The pacu caught from the neighborhood lake more than likely came from someone’s private aquarium. It was probably purchased as a smaller tropical fish at a pet store but then quickly became too large for the tank. Not wanting to destroy the fish, the kindhearted owner unwittingly released the pacu into the wild, thinking that it probably wouldn’t survive.

In fact, the pacu has shown a remarkable ability to adapt in different climates. A fish recently caught in a New Jersey reservoir was identified as a pacu. They have also been found as far west as California.

The introduction of non-native species has been happening in the United States for many years. In 1992, I was living in Florida and had to go to Miami on business. I decided to fish the Miami canals on the way home.

On my first cast, I hooked an “Oscar,” another fish that has made the aquarium-to-wild transition without a problem. Later, I caught a peacock bass, a South American cichlid that has found suitable habitat in the waterways. Twenty-five years later, the proliferation of invasive species has exploded in Florida, as well as expanding into other regions of the United States.

An invasive species threatens the balance of the local ecosystem by competing with and often supplanting native fish. The Asian carp is a prime example. This invasion has been documented many times, and many of the videos are available on YouTube.

One of the videos shows anglers coming home after a day on a northern lake. As the boat cruises a narrow channel, the water starts to erupt. Suddenly a throng of Asian carp begins leaping out of the water.

The man steering the boat laughs and holds out a landing net over the surface of the canal. Carp begin jumping into the net as well as the boat. Though it may have seemed humorous at the time, the reality is that such an overpopulation of non-native species can’t help but impact the indigenous fish habitat.

Perhaps the scariest invader is a fish called a snakehead. The snakehead is from Asia, where it has been deliberately cultivated as a food source. Snakeheads found in America were either introduced by residents or arrived in the ballasts of commercial tankers.

The characteristic that makes the snakehead most formidable is its ability to breath air. This allows the sinuous creature to slither over land and infect nearby bodies of water. With a mouth full of sharp teeth, no natural enemies and a ravenous appetite, the snakehead can easily put a dent in native fish stocks — if not wipe them out altogether.

Like the pacu, the snakehead has shown penchant for adapting to other regions of the country. It has been found in eight states, ranging from Florida to the Great Lakes. It has not turned up in New Hampshire so far, so we can count ourselves lucky.

Though the invasive breeds present an ecological problem, anglers have adapted in their pursuit of these fish. They don’t seem to care what they catch as long as they catch something.

YouTube is riddled with videos that show anglers proudly lifting a pacu or a snakehead in front of the camera.

It’s not all bad news. At the viewer’s convenience, fishing videos from around the world can be accessed. Anglers tend to present their most guarded secrets once the camera is turned on.

If nothing else, the invasive species videos could provide information that might prove useful for biologists who are trying to stem the proliferation of these unwanted interlopers.

Coleman Stokes can be reached at stokecoles@gmail.com.