Wildlife officials work to remove non-native koi fish illegally dumped in Boulder's Thunderbird Lake

Officials: Invasive koi harm native species

BOULDER, Colo. - State wildlife officials will try to remove hundreds of koi fish that were illegally dumped in  Boulder's Thunderbird Lake.

Koi and their close relative, goldfish, are both in the carp family, and are non-native species to Colorado and North America, according to state wildlife and Boulder parks officials.

Koi can thrive in widely ranging water quality conditions, driving out native species, officials said. They also carry several diseases that harm wild fish.

The illegal dumping of the koi, which may being naturally reproducing, will harm the lake's ecosystem and potentially other nearby water bodies, officials said.

On Monday, Colorado Parks and Wildlife staff will attempt to remove the koi fish from the lake. The fish will be used to feed osprey and great blue herons that are recovering from injuries at a local bird rehabilitation facility, officials said.

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