Workers with the City of St. Albert are working to gain the upper hand on an invasive species of fish that has taken over a storm water pond.

While they are the same type of fish often found at a pet store, without the limits of a fish tank, they grow exponentially and threaten native fish populations.

“As much as your cute goldfish is in your tank, as soon as you let it out into the natural environment they grow, they become very competitive,” Leah Kongsrude, City of St. Albert’s Director of Environment, said.

“I’m seeing fish that are 6 to 12 inches long so you compare that to a fish at a pet store, it’s one inch that’s pretty extraordinary in terms of growth.”

Now, crews are trying to keep the fish from spreading into other major bodies of water.

“We’re lucky in this situation; they’re just in the stormwater facility at this point, what we want to do is stop them before they get to the Sturgeon River,” Kongsrude said.

“The goldfish are an invasive fish species that basically means they can eat, and they can outcompete any of the native species. They can live in more low oxygen conditions, they can live in dirty water, and they also reproduce extremely quickly.”

Officials have tried to get rid of the goldfish in other ways, but they kept coming back.

“These fish are very hearty,” Kongsrude said. “For example, this pond, we pumped it down and froze it right to the bottom in the winter, and they were back in the spring. So they can live with very limited oxygen and low water temperatures.”

Crews were working Tuesday to cull goldfish from the body of water – they were spraying Rotenone, a chemical that only impacts fish, into the water. It works quickly, and it’s hoped it will kill the thousands of goldfish that have made the pond their home.

Plus, just to make sure the fish are completely removed from the pond, crews planned to come back later on. Crews will also focus on another nearby pond as well.

Officials are also reminding residents to not release any fish into any pond or body of water in the province – including flushing a fish down the toilet.

Alberta Environment has come up with what Kongsrude called the best way to dispose of a dead fish – a fish coffin.

With files from Nicole Weisberg