Colorado wildlife officials have started an investigation to trace who dumped thousands of goldfish into a Boulder lake two years ago.
What used to be four or five pet goldfish have now multiplied into thousands, which is a major threat to the lake's ecosystem.
The native species of Teller Lake #5 - including the channel catfish, bluegill fish and sunfish - are now being threatened by 3,000 to 4,000 goldfish that are non-native.
"Dumping your pets into a lake could bring diseases to native animals and plants as well as out-compete them for resources," Colorado Parks and Wildlife (CPW) spokeswoman Jennifer Churchill told ABC News. "Everything can be affected. Non-native species can potentially wipe out the fishery as we've put it together."
Wildlife officials are now thinking about electroshocking the fish or draining the lake to remove the goldfish from the water.
"With electroshocking, you go in the boat and stun the fish to paralyze and collect them," Churchill said, adding that the shock doesn't kill the fish. "The fish could also be collected if the lake is drained."
Some of the residents have volunteered to take the goldfish as pets, but the CPW is still thinking about it. They are worried that residents might throw them back in the lake if ever they don't want to take care of them anymore, which can restart the problem.
"Most people don't realize the far-reaching effects of introducing exotic species to the environment," Ken Kehmeier, senior aquatic biologist for CPW, told the Denver Channel.
"Nonnative 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."
Another proposal for the goldfish that will be collected from the lake is to bring them a local raptor rehabilitation program to use them for feeding.
