Calgary

Red Deer to remove invasive goldfish infestation from pond

A Red Deer storm pond is full of an infestation of goldfish, posing risks to native fish species and their habitat.

Fish were likely pets released by residents

Goldfish are seen swimming at a swimming hole in New Brunswick in this file photo. The City of Red Deer will remove the non-native species from a stormwater pond. (Julia Wright / CBC)

A Red Deer storm pond is full of an infestation of goldfish, posing risks to native fish species and their habitat.

It's not known how the goldfish got there, but the city believes it's likely due to people releasing their pet fish.

Now, the city will spray Anders pond with an odourless, natural pesticide to kill off its fish infestation — and ensure the non-native species doesn't spread to the Red Deer River or the city's stormwater management system. 

"Anything that is dumped in local storm ponds or storm drains will flow directly into our storm water system and into the Red Deer River," said Tim Ainscough, the city's environmental services manager, in a release.

"Removing invasive species will help to ensure that we maintain the aquatic health of our storm water system and local waterways."

Anders Pond will be fenced off from Sept. 9 to Oct. 21, while the city sprays a natural pesticide called Rotenone to kill off the fish and remove their carcasses.

It's toxic to fish species, but low to moderately toxic to birds, mammals, amphibians and inverterbrates. 

The city said Rotenone will be diluted and poses a low risk to people and land animals, adding that the chemical degrades through exposure to sunlight so the pond will be back to normal after a few weeks. 

"Consider re-homing your fish if you cannot take care of them, and if your pet first passes away, bury the carcass instead of flushing or dumping it, to avoid the spread of harmful bacteria," the city's release read.

Goldfish infestations have been a common problem in Alberta ponds.

The invasive species plagued Okotoks and St. Albert stormwater ponds for years, even surviving ponds freezing over winter and the water being treated with electric shocks.