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Dumped goldfish filling stormwater ponds in Okotoks almost under control

Okotoks is getting close to eliminating the huge goldfish that have been lurking in its stormwater ponds, but the problem could return if residents don’t stop dumping their unwanted aquatic pets.

People continue to dump unwanted pet fish into the town's waterways

Christa Michailuck looks over a stormwater pond in Okotoks that has been overrun with goldfish. (Terri Trembath/CBC)

Okotoks is getting close to eliminating the huge goldfish that have been clogging its stormwater ponds, but the problem could return if residents don't stop dumping their unwanted aquatic pets.

Christa Michailuck, an ecologist and parks manager for the town, has been working for the past year to get rid of goldfish in two of the town's stormwater ponds, which fill with runoff from streets and roads.

But it's not just a local problem. If the fish get into the nearby Sheep River, they could eat native fish and amphibian eggs, as well as root up the bottom of the river bed.

A large koi fish pulled out of a stormwater pond in Okotoks this weekend. (Terri Trembath/CBC)

"I think it will be an ongoing challenge that Okotoks and all municipalities will face with people wanting to continue to put fish like that into native ecosystems," she said.

Thousands of goldfish were pulled out of the Crystal Ridge stormwater pond on Friday after officials applied rotenone, an aquatic pesticide. It's the second pond they've had to address and will cost about $20,000, including a grant.

The largest goldfish found in the pond, nicknamed "fish number one," was 20 centimetres long and weighed 920 grams.

"Hopefully we can eradicate the goldfish from the two ponds we are focused on this year, but I think we need to be extra vigilant and not get to the situation where we have thousands and thousands in one little pond," Michailuck said.

Town staff will continue to harvest the goldfish this week and a final rotenone application will be done on the pond in a few weeks.

The provincial government launched an awareness campaign last year called Don't Let It Loose, aimed at informing Albertans about the dangers of releasing invasive species into waterways.

Christa Michailuck fishes dead and dying goldfish out a stormwater pond that has been treated with rotenone, an aquatic pesticide. (Terri Trembath/CBC)

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