Minnesota lake’s mutated goldfish now feeding zoo animals

Some of the goldfish have grown as large as 30cm to 40cm in length. Photo / City of Burnsville.

Mutated goldfish have overrun a Minnesota lake after years of residents dumping unwanted pets in the waters.

The massive creatures have made their home in Lake Cornelia, some doubling in size over the years they have been there, according to the Daily Mail.

But local organisations have devised a solution to the fishy problem.

The Minnesota Star Tribune reports a haul of 8,500 fish have been removed from the lake this year, frozen, and then taken to the local Minnesota Zoo.

There, they are fed to bears, sea lions, and the zoo’s singular otter.

Please don't release your pet goldfish into ponds and lakes! They grow bigger than you think and contribute to poor water quality by mucking up the bottom sediments and uprooting plants.
Groups of these large goldfish were recently found in Keller Lake. pic.twitter.com/Zmya2Ql1E2

— City of Burnsville (@BurnsvilleMN) July 9, 2021

While the fish are an ecological nightmare for local authorities, zoo nutritionist Kelly Kappen said “using local invasive species helps buffer us and gives animals more variety.”

Speaking to the Daily Mail, Kappen said zookeepers are repeatedly introducing the fish to the zoo’s animals to see what works best.

“Early results are promising, and we look forward to expanding this initiative in the years ahead as part of our ongoing commitment to animal wellness and environmental stewardship.”

In the past, the mutated fish were removed and composted on farms in an effort to keep the lake usable.

This year’s fish haul is still a massive reduction from the numbers counted in previous years.

In 2023, volunteers trawled a staggering 50,000 goldfish from the lake by hand.

Carp Solutions owner Przemek Bajer told CNN the invasive fish are removed because they disrupt the lake’s delicate natural ecosystem.

“Often, they don’t eat aquatic plants, but the plants simply cannot establish roots in those lakes, they’re just uprooted physically.”

The goldfish also “turn clear lakes into green lakes” by stirring up sediment as they search for food.