The province is launching a campaign this summer to stop people from releasing their pet fish into the wild.
Goldfish, some the size of dinner plates, are being found from Lethbridge to Fort McMurray, the province says.
"It's quite a surprise how large we're finding them and the sheer number," said Kate Wilson, aquatic invasive species co-ordinator at Alberta Environment and Parks.
In one case, the municipality of Wood Buffalo pulled 40 of the domestic fish species from a storm water pond.
"That's really scary because it means they're reproducing in the wild, they are getting quite large and they are surviving the winters that far north," said Wilson.
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Wilson says the government's Don't Let It Loose campaign will focus on educating Albertans about the dangers of releasing domestic fish into nature.
"Approximately a third of invasive species out there that threaten native aquatic environments are from aquariums and the ornamental trade," she said.
Wilson says the campaign will target pet stores, businesses that supply ponds and aquariums, Asian markets that sell live fish and spiritual groups that release captured animals as an act of good karma.
Prussian carp also threat
Another invasive species spotted in the Bow, Rosebud, Red Deer and South Saskatchewan rivers is the Prussian carp.
According to Wilson, Alberta is the only jurisdiction that's reported the foreign fish in its waterways.
"Something weird is happening," she said.
"It could be a group of people from somewhere else who are used to fishing for these kind of species which intentionally introduced them, which is highly illegal."
We initially reported that Alberta Environment and Parks said goldfish are making their way into the province's waterways, in part, because they are flushed down the toilet. In fact, the "Don't Let it Loose" campaign is only focused on fish and other invasive aquatic species being directly released into the waterways.Jun 25, 2015 1:59 PM MT