Discarded pet goldfish overran an Edina lake, and it’s a win for bears at the Minnesota Zoo

The nets tightened, and the lake erupted. Bronze scales flashed, water churned and a heap of orange-hued fish thrashed against the mesh as crews pulled them toward shore.

They weren’t perch or sunfish — they were descendants of former pets, the goldfish won at carnivals or bought in pet stores, long ago dumped in Lake Cornelia and left to multiply. Some were no bigger than a hand, others stretched the length of a forearm, with a few growing close to a foot long.

Those discarded prizes have since grown into an ecological headache in some Minnesota lakes. Bottom feeders like their carp cousins, the goldfish churn up sediment, release phosphorus and fuel algae blooms that cloud the water and crowd out native species.

That’s why the city of Edina and the Nine Mile Creek Watershed District have made their removal a priority, and this summer, trucked them to a place where, for some wild residents, the goldfish are appetizing and in-demand: the Minnesota Zoo.

Week after week, nets are baited and sprung, workers wade in with buckets, and the goldfish are hauled away.

“I was standing there looking at this writhing mass of fish as we emptied it into buckets,” said Peter Mans, an Edina water resources intern who spent the summer elbow-deep in the fishy-smelling project. “I had no idea this was in the lake. Nobody would have any idea.”

The numbers are staggering. In 2023, crews pulled around 50,000 goldfish — weighing more than a ton altogether — from Cornelia’s two basins. By this year, the haul had dropped dramatically: about 8,547 goldfish weighing 1,716 pounds through the 2025 season so far, according to Jordan Wein, a water resources project manager with Nine Mile Creek Watershed District.

For years, the heaps of goldfish pulled from the lake ended up in farm fields, dumped and buried. This year’s harvest brought a more creative solution.

Through a connection between Minnesota GreenCorps alumni, the watershed struck up a partnership with the Minnesota Zoo. Instead of rotting underground, Cornelia’s goldfish were loaded into coolers, packed into the zoo’s freezer and rolled out for feeding time.

“Zoos have historically over-relied on a very small number of fish species,” said Kelly Kappen, zoo nutritionist. “Using local invasive species helps buffer us and gives animals more variety.”

It also cuts down on waste.

“While they were composting perfectly edible fish, we were purchasing fish harvested intentionally for food,” she said.

Tigers and leopards wouldn’t touch them. Black bears stuck to their vegetarian diets. Sea lions eyed the new food suspiciously, nibbling one or two a day. But the brown bears?

“Our brown bears are really enjoying it,” Kappen said. “Our sea lions are still getting used to the idea — they’re eating a few of them, but a lot of our carnivores are kind of neophobic anytime that they’re introduced to a new food.”

Back at Lake Cornelia, the tally tells its own story. North Cornelia yielded nearly 7,900 goldfish, while South Cornelia produced fewer than 700. And though the total number of the invasive fish continues to fall, the total weight has barely dipped.

“That’s actually good news,” Wein said. “It means we’re not seeing new generations of little fish, and that gives native species a chance to rebound.”

The city has plenty at stake. Cornelia anchors a neighborhood park, its shoreline dotted with trails and playgrounds. For Edina, restoring it means cleaner water, healthier ecosystems and a lake that residents can actually enjoy.

The nets will stay in the lake through fall, each haul a step toward clearer water and healthier native fish, plus a meal for the bears.

For Mans, heading into his senior year studying environmental science, the project was a crash course in the strange, smelly intersection of animals, science and local government.