Released Goldfish Prompt Woodbury Pond Treatment
Pet owners who release fish into public waters can trigger costly cleanups that affect nearby shoreline homes.
Updated on Oct. 31, 2026 in Aquariums
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Woodbury city officials obtained a state permit to use rotenone to eliminate an invasive goldfish population in a stormwater pond linked to Powers Lake. Released pet goldfish established the population, and the district issued its public notice describing the case on August 14, 2026.
Why it matters
Goldfish stir up pond sediment and release phosphorus, which feeds algae blooms that can degrade the water quality homeowners see from their shorelines. Minnesota law treats releasing goldfish into public waters as illegal fish stocking, so pet owners who let a fish go can end up contributing to a costly cleanup on a lake their neighbors rely on.
Goldfish can grow up to 6 pounds, and experimental tanks showed up to an 81 percent rise in suspended mineral particles. The 2017 study used 32 tanks of 320 gallons each over 61 days.
The players
City of Woodbury
The Minnesota city that obtained the state permit and carried out the goldfish removal in its stormwater pond.
Minnesota Department of Natural Resources
The state agency that discourages rotenone use and oversees fish stocking rules and the permit process for treatments in public waters.
U.S. Fish Commission
The federal agency that distributed goldfish to 37 states between 1878 and 1893, an early source of the species' spread.
The details
Crews tried to remove the goldfish using sonar, electrofishing, and baited box nets before turning to rotenone, a fish toxicant derived from tropical plant roots. Rotenone kills fish by entering through their gills, which is why the state requires written agreement from every shoreline owner before application. Minnesota's Department of Natural Resources discourages rotenone use, so the state permit reflects a decision that the invasive population posed a serious enough threat to justify it. Treatment and cleanup are expected to take one day, after which native fish species are expected to return to the pond.
Timeline
Between 1878 and 1893, the U.S. Fish Commission distributed goldfish to 37 states.
In summer 2017, a university research team ran a 61-day tank experiment on goldfish.
In 2019 and 2021, alum treatments were performed at Keller Lake.
On July 8, 2026, the district issued a notice about the risk of goldfish migrating into the pond.
On August 14, 2026, the district released a public notice describing the Woodbury case.
The Home Front
The Woodbury cleanup traces back to the U.S. Fish Commission's 1878-1893 distribution of goldfish to 37 states. Today the same spread happens one pet owner at a time, which is why lakeside homeowners in the Twin Cities region are feeling the effects on their shorelines.
If you keep goldfish, never release them into a pond, lake, or stormwater pond, since Minnesota treats that as illegal fish stocking. If you no longer want your fish, contact a local aquarium shop or animal shelter about rehoming them.
The takeaway
A goldfish that grows to 6 pounds and stirs up sediment can change a pond's water quality for years, so a release that seems harmless can have lasting costs for lake neighbors. Keep pet fish in their tank, and check with your local Department of Natural Resources office before you consider any pond or lake treatment.
Further reading
For more on how aquarium fish end up in local waterways and what to do instead of releasing them, browse our Aquariums section.
Source note: This article includes information reported by ECOticias.
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