The tiny fish creating big problems in B.C. waterways

They’re a popular fish for aquariums, but they’ve become a growing problem in the wild. 

Unwanted goldfish, illegally dumped in B.C. waterways, are threatening native species and there are calls for the province to take action.

It’s a topic that netted attention at an invasive species forum held in New Westminster this week.

"(Goldfish) cause so many problems, we just don’t want them in those lakes,” said Brian Heise, who works in the Natural Resource Sciences department at Thompson Rivers University and was also a speaker at the forum.

Inside a tank, goldfish are tiny, but Heise said they grow far bigger in the wild.

“The biggest goldfish we have seen around the world have occurred in Australia…And there they’re getting up to 41 centimetres long which is huge, just a massive thing,” Heise said.

He said in B.C., goldfish 24 centimetres long have been found.

“They’re causing turbidity which is suspended sediments in the water that interferes with the feeding of local fishes,” Heise explained.

“They also will uproot plants and that causes problems for plant growth in some of our lakes and they also could pass on diseases to some of our salmon and trout as well."

In Quesnel, Dragon Lake has battled a goldfish invasion for years. Thousands of goldfish have been pulled from there, but Heise said the problem persists.

“They’re very quick to come back and create a large population and it’s pretty tough to control them.”

Governments and organizations have been trying to educate people about the risks of dumping unwanted goldfish into waterways, but where the goldfish have already been established, there are calls for the province to take more direct action

Heise said Quesnel has used a method called electrofishing to try and decrease the population. He wants the province to fund wider-use for problem lakes.

He also thinks pet stores should be obligated to take back goldfish that are no longer wanted as pets.

“If they’re allowed to sell all of these exotic animals that aren’t native to Canada, then basically they have a responsibility for what happens to those animals once they’re sold,” he said.

More information on invasive goldfish can be found through the province as well as the Invasive Species Council of B.C.