Foot-long goldfish invasion prompts drastic action at Minnesota lake
Edina's Lake Cornelia battles a mutating influx of dumped pet goldfish, leading to mass removals and a new feeding program at the Minnesota Zoo.
Edina, Minn. — Lake Cornelia is overrun with pet goldfish dumped by residents, some mutated to about a foot in length, prompting a major removal effort. Through this year, authorities have pulled more than 8,500 goldfish, weighing roughly 1,700 pounds, from the lake’s two basins, according to Jordan Wein of the Nine Mile Creek Watershed District, which is coordinating the effort.
In 2023, about 50,000 goldfish were removed from the lake. While the number has fallen, the total weight of the catch has stayed similar because some goldfish have doubled in size. Peter Mans, an Edina water resources intern, said he spent the summer in what he described as a writhing mass of fish, emptying buckets of the catch on a weekly basis to keep the lake from fouling. Crews set nets in the water and hand-select each goldfish, allowing perch and bluegills to swim free. The cleaned goldfish are then taken to the Minnesota Zoo.
At the zoo, the goldfish are used as food for brown bears and sea lions, a shift from previous disposal methods. Zoo nutritionist Kelly Kappen explained that using locally invasive species can diversify diets and bolster animal wellness. The zoo had previously composted goldfish on farm fields, but now purchases them for use as feed.
Animal responses have varied. Early results show brown bears consuming the goldfish, and sea lions tentatively eating them, while North American river otters have sampled goldfish and rusty crayfish. Some species, such as black bears, tigers, and leopards, have shown little interest.
City officials say the goal is to restore Lake Cornelia to a condition where it is fishable and usable for residents. Nets and removal work continue as crews try to reduce the population and prevent further ecological disruption in the lake, which already poses odor issues during the removal season.
City officials note that the goldfish problem highlights a broader issue seen across inland lakes: pet releases can become invasive, alter ecosystems and require costly, ongoing management.