Goldfish Invading Ponds in Okotoks Alberta (PHOTO)

Pet goldfish are small little fish that can bought from any local pet shop.

In fact, most people would not think of them as an environmentally disrupting invasive species. That said, a number of pet owners have grown tired of maintaining the fish and rather than flush them down the toilet, they do what they believe is the humane thing to do: set them free in the wild.

Now, hundreds of wild, measuring up to 25 centimeters long, have overrun two storm water ponds in Okotoks Alberta.

Envirnonmental officials in the province are now concerned the fish could end up in the Sheep and Bow rivers and their tributaries, where they could out-eat and out-live native fish while spreading disease among plants.

“They have no natural predators, and they can grow really large and get out into the natural ecosystem and cause all sorts of problems,” said Bridget Couban, landscape inspector with Okotoks’s parks department.

Invasive species experts in Alberta are warning people against flushing live goldfish down the toilet, after several specimens the size of dinner plates were pulled from ponds in different areas of the province.

In 2015, more than three dozen goldfish were pulled from a storm pond in Fort McMurray last summer, including some as long as 20 centimetres in size. Wilson says officials found evidence that the fish were breeding and surviving through Fort McMurray’s cold winters, which suggests their numbers are growing.

Aquarium Owners

Water gardeners, pond and aquarium owners have a number of responsibilities, including:

  • taking good care of the species that they keep
  • ensuring their artificial water environment stays isolated from the outside environment
  • when necessary, disposing of the fish or plants from that environment in a safe and humane manner

Do not dispose of plants and fish from aquariums and ponds into an Alberta stream, lake or river system. Releasing them disrupts the natural balance of Alberta’s ecosystems, and ultimately results in biodiversity loss.

For example, koi and goldfish released from ponds and aquariums can survive Alberta’s climate and grow to be very large. They have no natural predators in Alberta and will out-compete native species for resources.

It is illegal to release live fish into Alberta’s lakes or rivers. Fines can be up to $100,000.

If you are no longer able to care for a fish from your pond or aquarium, do not release it into a lake or river. Try:

  • Contacting the retailer for advice, or for a possible return
  • Giving it to another aquarium or pond owner
  • Donating it to a local aquarium society or school
  • Talking to a veterinarian about humane disposal


Do not transfer live fish from one water body to another.

  • It is illegal to move live fish from one water body to another. Doing so disrupts the local ecosystem, threatens the existing fish population and, if a stocked fishery, jeopardizes the future of that fishery.
  • Fish that are illegally released into a stocked fishery can undermine efforts to maintain that fishery for the enjoyment of all Alberta anglers.
  • Once an illegal introduction has occurred in a stocked fishery, the efforts to restore it are extremely expensive and can bring some harm to other parts of the local ecosystem.
  • Penalties for illegally transferring fish into any water body aside from the one it was caught in can be up to $100,000 and/or a year in prison.
  • Fish introduced from outside of Canada can cause significant damage to local fish populations. Though not currently found within Canadian waters, the silver and bighead carp are threatening to find their way to the Great Lakes. These fish, introduced into US waters from Taiwan, are voracious eaters and out-compete native trout and salmon. These carp are also known for their capacity to leap out of the water, creating a hazard for water skiers and boaters.
  • To prevent the introduction of invasive worm species put unused bait back in its original packaging and put it in a garbage container.
  • Do you wear waders when you fish? Felt-soled waders are highly absorbent and, if not properly cleaned, can transfer invasive species from one water body to another. Soak them in hot water for at least 40 minutes after every use, or better yet, switch to non-felt-soled waders.

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