When you think of “invasive” species, critters like zebra mussels, Japanese beetles, and Burmese pythons probably come to mind. But how about … goldfish?

Well believe it or not, wildlife authorities from Minnesota, Colorado, Virginia and many others are sounding off about the alarming number of goldfish that are finding their way into ponds, lakes, rivers and other waterways across the U.S.A.

Likely released into the wild by pet owners, goldfish can be a pest, say experts, because of their ability to muck up water quality, uproot plants, and harm native fish species. They can also grow quite large — some attaining the size of a football in the wild. In 2013, Scientific American reported that a goldfish was caught in Lake Tahoe that was 1.5 foot long and weighed a whopping 4.2 lbs!

While a few here and there aren’t such a big deal, officials claim the numbers of goldfish now being found in the wild has become alarming. Indeed, 50,000 were recently removed in Carver County, MN, and some 3,000-5,000 were also discovered to be swimming around waterways in Boulder, CO, according to researchers.

Cleaning up waters contaminated with too many goldfish is costly. As reported in the UK Guardian:

The costs of rehabilitating waterways infested with goldfish is substantial. Carver county in Minnesota signed an $88,000 contract with a consulting firm to study how to eradicate shoals.

The Washington Post reported that in 2018 Washington state officials said they would spend $150,000 rehabilitating a lake near Spokane. In Alberta, Canada, an invasive-species expert called a goldfish problem ‘scary’.

It is estimated that as many as 200 million goldfish are bred each year, most ending up on domestic display.”

To read more on this issue, visit EcoWatch by clicking here.


  • Craig Rucker

    Craig Rucker is a co-founder of CFACT and currently serves as its president.