Releasing pet fish into a lake might sound like a kind thing to do, but in fact, it is quite the opposite. Teller Lake in Boulder, Colorado, is making headlines for a bizarre surge in its goldfish population, after someone apparently dumped three or four of them in its waters a couple of years ago. The lake is now home to a whopping 3,000 to 4,000 goldfish that are putting its delicate ecosystem in danger.

The fish have multiplied beyond control – they’re eating up all the resources, spreading unnatural diseases, and threatening to overrun the lake’s natural species. Colorado wildlife officials say that humans are to blame.

“Dumping your pets into a lake could bring diseases to native animals and plants as well as out-compete them for resources,” said Colorado Parks and Wildlife (CPW) spokesperson Jennifer Churchill. “Everything can be affected. Non-native species can potentially wipe out the fishery as we’ve put it together.”

Photo: Colorado Parks and Wildlife

“Most people don’t realise the far-reaching effects of introducing exotic species to the environment,” added CPW senior aquatic biologist Ken Kehmeier. “Non-native species can be devastating to native populations by causing disease outbreaks and creating competition unbalance. It’s an issue that anyone concerned with our environment should know about.”

A special crew is now attempting to get rid of all the unwanted goldfish, and they’re faced with two difficult options – either drain the 12-acre lake completely, or use electrofishing to stun the fish using an electrical current. The stunned fish would rise to the surface of the lake, and could then be cleared.

Photo: Colorado Parks and Wildlife

“With electroshocking, you go in the boat and stun the fish to paralyze and collect them,” Churchill explained, adding that the fish are not killed in the process. The technique has been used successfully in the past – at Boulder’s Thunderbird Lake in November, 2012, to get rid of koi goldfish that were also improperly introduced. Approximately 2,200 fish were removed using the process, which is most likely to be used at Teller Lake as well.

Once caught, the fish will most likely end up at a local raptor rehabilitation program as food. Officials are warning locals against catching some of the goldfish to take home and raise as pets. “I’m going to talk to Boulder County, who owns the lake to see what they think, but I don’t want to send the message that collecting fish for personal fun is okay,’ Churchill said.

Meanwhile, reactions to the story – reported by ABC News – have been varied. Some refused to even acknowledge it as an ecological disaster. “I do find it kind of humorous that we are worried about an invasive species thriving in a manmade lake. The lake itself is invasive,” one person commented.

Others provided innovative solutions like cats, but this one guy wrote: “Release a bunch of snapping turtles into the lake to eat the goldfish. Then release a bunch of alligators to eat the turtles. Then open an alligator hunting season. Everyone wins.”