Goldfish attack! Unwanted carp showing up in High River ponds

The town of High River has some unwanted guests swimming in its stormwater system — dozens of goldfish set free by pet owners.

"When I went up there and saw them, the biggest one that I saw was maybe five inches long," said High River's Mayor Craig Snodgrass.

"If they make it through our stormwater system and make it to the Highwood River, once you get these carp and goldfish into a river system like that, they're not native species and they will destroy those rivers," he said.

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Where goldfish go, algae tends to follow, and that could create a smelly problem at the town's storm water ponds.

"The amount of waste that they produce, you might as well just run a fertilizer spreader through your storm pond every two weeks, because that's what these fish are doing," he said.

"The algae will go absolutely nuts."

And local residents will too, he says.

"The next thing that comes to us is the residents are mad because the ponds are covered in algae, and they stink, and they don't look very nice etc., so that's where we're headed with these fish."

'Don't Let It Loose' campaign

Earlier this year, Alberta announced its "Don't Let It Loose" campaign to educate people about the dangers of releasing domestic fish into nature. It said goldfish, some the size of dinner plates, are being found from Lethbridge to Fort McMurray. 

"There's pet stores in Calgary that have programs actually to take your backyard fish and hold on to them over the winter and you can exchange them for new fish in the spring again," said Snodgrass.

He is telling residents that if they love their fish, don't set them free, because the fate of those golden domesticated members of the carp family won't be pretty.

"I know that they were trying to do the right thing in setting these things free, but the problem is now we've got to go in and kill 'em."