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Goldfish are invading Canada’s lakes and ponds

goldfish invading lakes
goldfish invading lakes
Tiny terror: In the wild, the common goldfish can grow to as large as ten pounds.

Goldfish are becoming a problem in Canadian waterways and experts are having a hard time figuring out how to get rid of them.

“The crazy thing about goldfish is they’re so hardy, that’s why they’re so popular in the aquarium world,” says Kate Wilson, aquatic invasive species specialist with Alberta Environment and Parks.

The problem starts when people who no longer want their pet store bought goldfish and decide to release them into the wild rather than kill them.
First domesticated in China, goldfish are not native to Canadian lakes and rivers but they thrive here nonetheless, having no natural predators as well as seemingly no problem dealing with our cold temperatures or low-oxygenated waters.

Edgewater Pond in St. Albert, Alberta, is dealing with hundreds of goldfish that are continuing to reproduce and grow to huge proportions. “Some were probably finger tips to elbow [in length],” said Sarah Cicchini, an environmental coordinator with the city of St. Albert.

Apparently, the city has made numerous attempts to get rid of the fish. They tried draining the pond to the point that it would freeze all the way through (this winter didn’t get cold enough for that), they tried netting and electrocuting them (the fish apparently enjoyed the excitement -kidding), they are even contemplating adding poison to the pond to kill the invaders.

“People think this is a humane thing to do. But this practice is very harmful to native species, to Alberta waters, to our biodiversity and the fish that actually belong here,” says Wilson. In fact, she advises that if and when owners no longer want to care for their fish that they do not flush them either, as this takes whatever diseases and parasites the fish might have had and puts them in our water system. “We are not advocating that even dead fish be flushed,” says Wilson.


Goldfish are invading our lakes. And they’re getting HUGE…


In the wild, the common goldfish can grow to as large as ten pounds.

According to the CBC, Hamilton Harbour in Ontario is also being hit with a shimmery golden invasion, with researchers at the Royal Botanical Gardens reporting that they counted at least two-million goldfish in the bay. Tys Theysmeyer, a researcher with the Royal Botanical Gardens attributes the goldfish’s rise to higher water temperatures and poorer water quality, both of which have caused native species such as northern pike and minnows to decline in numbers and thereby leaving more space for the goldfish to thrive.

Goldfish are a problem in other parts of the world as well. Recently in Japan where, as in Canada, releasing goldfish and other non-native species into waterways is illegal, a pair of scientists found evidence of the first case in ten years of illegal release of bluegill fish along with goldfish into the country’s water, with the help of an undergraduate who captured images of the fish in an outdoor pool in Yokohama city and tweeted the images.

And in England, researchers at the University of Exeter have found that the presence of exotic fish such as goldfish in local lakes and ponds is devastating the frog population. According to the researchers, the presence of the fish either amplifies viral levels in the environment or causes stress hormone production in the frogs which reduces their immune function.


Below: Flushed Goldfish Prompt Invasive Species Scare In Canada


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About The Author /

Cantech Letter founder and editor Nick Waddell has lived in five Canadian provinces and is proud of his country's often overlooked contributions to the world of science and technology. Waddell takes a regular shift on the Canadian media circuit, making appearances on CTV, CBC and BNN, and contributing to publications such as Canadian Business and Business Insider.
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One thought on “Goldfish are invading Canada’s lakes and ponds

  1. It’s really quite a shame that they are a nuisance as they are relatively intelligent for a fish.
    Also a good source of protein. Soylent orange is made of fish. 😛

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