Aquatic Invasive Species

An aquatic invasive species is a non-native organism that has been brought from other places into Alberta’s water. These species cause – or have potential to cause – harm to our environment, economy, and human health.

Aquatic invasive species to look out for

Quagga and Zebra Mussels 


Some specific species that pose a risk to our waterways within Medicine Hat and area include Zebra and Quagga mussels. They have potential to cause significant negative impacts on water quality, aquatic ecosystem, and potential to clog water intake lines and City infrastructure.

photo of quagga mussel

Quagga Mussel

photo of zebra mussel

Zebra Mussel


Whirling Disease 

Whirling disease is a microscopic parasite that affects salmonid fish such as trout, salmon, and whitefish. The disease can cause health issues such as skeletal defects to the fish which typically leads to mortality in 90% of cases. 

Eurasian Watermilfoil 

An aquatic plant that grows under the water surface and spreads rapidly invading/replacing native plants. It can negatively affect fish, native aquatic vegetation, wildlife populations and human activities.

If you suspect any of these species in our waterways, please report them promptly, through the Alberta Invasive Species hotline 1-855-336-BOAT (2628) or on EDDMapS Alberta.


We must protect our waterways throughout Medicine Hat to ensure they can remain open for recreational use, and for the health of the aquatic environment. Some restrictions seen across the Country and Province for the 2024 season include:

  • Lakes, creeks and tributaries in Eastern British Columbia have already announced closures due to the presence of whirling disease found in the fish.
  • Waterton Lakes and National Park has restricted the access of non-motorized watercraft from outside the park, to protect against whirling disease, zebra and quagga mussels.

The invasion of zebra and quagga mussels into nearby Medicine Hat waterways would come with significant economic damage. Hundreds of millions of dollars have been spent throughout North America since the discovery of the invasive mussels. BC predicts to spend between $64-$129 million dollars annually to resolve damages to infrastructure, property values, and lost business opportunities due to zebra and quagga mussels.

How to stop the spread of Aquatic Invasive Species including Whirling Disease?

Clean + Drain + Dry your gear before transferring between waterbodies (this includes watercrafts, kayaks, paddle boards, paddles, life jackets, construction equipment, etc.)


  • Clean and inspect all items used in water including but not limited to watercraft, trailer, and gear.
  • Remove all plants, animals, and mud at the access area or dock.
  • Rinse, scrub or pressure wash your boat away from storm drains, ditches and waterways. Use hot water if possible (max 60 degrees Celsius).


  • On land, before leaving the waterbody, drain all water from bait buckets, ballasts, bilges, coolers, internal compartments, live well, etc.
  • For paddle boats, kayaks and canoes, drain by inverting or tilting the watercraft, opening compartments and removing seats if necessary.


  • Dry the watercraft and gear completely between trips.
  • Leave compartments open and sponge out standing water.

Aquatic invasive species are regulated federally under the Fisheries Act and provincially under the Fisheries (Alberta) Act

A full list of aquatic invasive species in Alberta can be found in the Aquatic Invasive Species Pocket Guide.

Don't let it loose logoInvasive species at home

Goldfish and koi are non-native species and are considered to be invasive because of the adverse effects they can have in areas like retention ponds. Without any natural predators, goldfish and koi can outcompete other species in the area, creating an unbalanced and unhealthy ecosystem that is costly to fix. 

See how a senior fish biologist used pesticide in Leinweber pond.

Never use goldfish or koi as bait, dead or alive. Penalties for introducing a fish into any waterbody other than where it was found can be up to $100,000 and/or a year in prison. Do not flush it, and do not place it in a local body of water.

If you are no longer able to care for a fish in your aquarium or pond, the Government of Alberta recommends: 

  • Contacting a retailer or pet store
  • Giving it to an aquarium or pond owner
  • Donating to a school 
  • Talking to a veterinarian

If your pet goldfish passes on, please bury it or dispose of it in the garbage to prevent the spread of disease. Pet owners who intend to dispose of fish can drop by the Parks and Recreation office to pick up a biodegradable fish burial pod free of charge.

For more information, visit the Government of Alberta website.