A Fishy Solution: Zoo Animals Feast on Invasive Goldfish
In a creative approach to wildlife conservation, Minnesota zookeepers have found an ingenious solution to the growing problem of invasive goldfish in American waterways. The common practice of pet owners releasing unwanted goldfish into local lakes and ponds has led to an ecological crisis across several states, with these seemingly innocuous creatures transforming into oversized invaders that threaten native ecosystems. Rather than sending these captured fish to landfills or compost facilities, the Minnesota Zoo in Apple Valley has begun implementing a bold new initiative: serving them as meals to zoo residents. This innovative approach addresses two problems simultaneously—controlling invasive species populations while providing nutritious food for captive wildlife. “Early results are promising,” reports Kelly Kappen, a nutritionist at the Minnesota Zoo where this conservation initiative is being trialed.
The scale of the goldfish invasion is staggering, particularly in Minnesota’s Lake Cornelia, where thousands of discarded pet goldfish now outnumber native species. What many pet owners fail to realize is that these small aquarium fish, when released into natural water bodies, can grow to an astonishing four pounds. This practice, termed illegal “fish stocking,” creates multiple environmental problems. The goldfish disrupt natural ecosystems by competing with native fish for resources, uprooting aquatic plants, and potentially spreading diseases. According to the Nine Mile Creek Watershed District, these invasive goldfish “stir up the bottom of the lake, releasing phosphorus that fuels algae blooms and clouds the water.” The environmental impact extends beyond just competing with native species—these goldfish fundamentally alter the water chemistry and clarity, creating cascading effects throughout the ecosystem.
The Minnesota Zoo’s innovative approach comes from a partnership with the Nine Mile Creek Watershed District, turning an environmental problem into a practical solution. Previously, when conservation teams removed invasive fish from waterways, the captured goldfish and carp would typically end up in landfills or compost sites—hardly an efficient use of this potential resource. Now, these harvested invasive species, including both goldfish from Lake Cornelia and carp from Minnesota rivers, are being repurposed as nutritious meals for zoo animals. This creates a sustainable food cycle that benefits both the natural environment and captive wildlife. The program represents a creative form of ecological management that transforms invasive species from environmental liabilities into valuable resources, demonstrating how conservation challenges can sometimes lead to unexpected opportunities for innovation.
Introducing new food sources to zoo animals requires careful planning and patience, as Kappen explains: “We are working with a limited number of partners to ensure safe food handling, and inclusion in animal diets is carefully evaluated as part of a well-balanced and individualized diet plan.” The transition hasn’t been without challenges, as many animals approach unfamiliar foods with caution. “Many animals are suspicious of new foods, so repeated introductions are often necessary for these new options to be consumed,” Kappen notes. Despite initial hesitation, several species have begun embracing these new menu items. Brown bears have shown particular enthusiasm for carp, while sea lions are gradually warming up to goldfish. River otters have been more adventurous, sampling both goldfish and rusty crayfish—another invasive species being incorporated into the feeding program. These early successes suggest that the program has significant potential for expansion.
The goldfish invasion extends well beyond Minnesota’s borders, affecting waterways in Colorado, Nevada, and Pennsylvania. These invasions highlight the widespread nature of the problem and the potential for similar solutions to be implemented nationwide. In a particularly striking case, officials with the US Fish and Wildlife Service recently removed a massive “megalodon” goldfish from a pond in Erie, Pennsylvania. Experts believe this enormous specimen had been living in the wild for up to two years after being released by its owner. This dramatic example underscores how quickly released aquarium fish can adapt to their new environments and grow to unexpected sizes. “Someone released it, thinking they were being kind,” officials noted. “Instead, they created an invasive problem that can last decades.” This poignant observation captures the unintended consequences of well-meaning but ecologically harmful actions.
As the Minnesota Zoo continues to refine its approach, the institution hopes to expand this innovative feeding program as part of its “ongoing commitment to animal wellness and environmental stewardship.” The initiative represents a promising model for addressing invasive species challenges through creative, practical solutions that benefit multiple stakeholders. Beyond the immediate advantages for ecosystem health and zoo animal nutrition, the program serves an important educational purpose by raising public awareness about the ecological consequences of releasing pet fish into natural waterways. By transforming an environmental problem into a solution, the Minnesota Zoo demonstrates how conservation challenges can sometimes be addressed through unexpected approaches that create positive outcomes for both natural ecosystems and captive wildlife. This goldfish-to-food-chain initiative may represent just the beginning of similar innovative approaches to invasive species management across the country.
