Following the removal of several giant goldfish from a local lake, authorities in Minnesota have urged aquarium owners to refrain from releasing pet fish into waterways.

'Is this Yours?': Owner of Supersize 9-Pound Goldfish Remains Unknown
(Photo : Photo by Greenville Rec on Facebook )


Released goldfish may grow to several times their usual size and wreak havoc on native species, according to officials in Burnsville, some 15 miles south of Minneapolis.

On Friday, the city tweeted, "Please don't release your pet goldfish into ponds and lakes!" "They grow bigger than you expect and muck up the bottom sediments and uproot vegetation, contributing to poor water quality."

Officials in adjacent Carver county removed up to 50,000 goldfish from local waterways last November. According to Paul Moline, the county's water management manager, "are an understudied species" with "a significant potential to severely influence lake water quality."


Goldfish, like carp, can readily multiply and live in low-oxygen environments throughout the Minnesota winter.

The Minnesota Department of Natural Resources warned, "A few goldfish might seem like an innocuous addition to the local water body - but they're not."

Related Article: Growth of Damaging and Invasive Species Linked To Pet Trade

Goldfish as an Invasive Species

Giant Goldfish
(Photo : Wikimedia Commons)

Although goldfish have gotten less attention than other invasive species like Asian carp and zebra mussels, warnings have been issued in Virginia, Washington, Australia, and Canada.

According to Scientific American, researchers combing Lake Tahoe in 2013 caught a goldfish that was over 1.5 feet long and weighed 4.2 pounds. "Globally, the aquarium trade has contributed a third of the world's worst aquatic and invasive species," according to the author of research on California's aquarium trade.


After an angler captured a 16-inch goldfish, wildlife authorities in Virginia issued a warning that "pet owners should never release their aquatic creatures into the wild."

The expenses of restoring goldfish-infested rivers are significant. For example, a consulting business in Carver County, Minnesota, was awarded an $88,000 contract to explore ways to remove shoals.

According to the Washington Post, Washington state officials announced in 2018 that they will invest $150,000 to rehabilitate a lake near Spokane. In addition, a goldfish problem has been described as "frightening" by an invasive species specialist in Alberta, Canada.

Each year, it is believed that up to 200 million goldfish are bred, with the majority of them ending up in residential aquariums.

Goldfish Adoption

(Photo : Wikimedia Commons)

Pet owners who no longer want their goldfish should either put it up for adoption (yep, even furry pals get a second shot at life) or contact a local vet or pet store on how to properly euthanize and dispose of it, according to the US Fish and Wildlife Service.

Social Conditions

When goldfish are released into the wild, they form what is known as a school. However, they do not require the company to be happy in captivity and may be maintained alone in a tank.

Because they aren't aggressive, they may be kept in a tank with fish of similar sizes. They're also smarter than they appear. The researchers discovered that they can be taught to distinguish between Bach and Stravinsky's classical music.


Goldfish in captivity generally consume pellet or flake food. Supplements, on the other hand, are suggested to more closely resemble their natural diet. Worms, larvae, tiny crustaceans like brine shrimp, and even salad fixings like peas and lettuce are eaten by them in the wild. Goldfish owners should add foliage to their bowls since the fish like eating real plants.

Also Read: Top 5 Most Destructive Invasive Species Today

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