Invasive Goldfish Management
The City of Spruce Grove has positively identified invasive goldfish (Carrassius auratus) in the Easton stormwater management facility (SWMF). After extensive consultation with Alberta Environment and Protected Areas (AEPA), the City has initiated a comprehensive goldfish management strategy.
Considered an invasive species by the Government of Alberta, goldfish pose several risks to stormwater and natural aquatic systems including:
- possibly carrying pathogens that may infect other fish species
- destructive feeding behaviour that increases water turbidity, degrading habitat and reducing food availability for native species
- potential contribution to algal blooms through nutrient cycling and sediment disturbance
Goldfish have several characteristics that create a high potential of spread to connected waterbodies if not effectively contained. They:
- are extremely hardy and able to tolerate low oxygen levels and poor water quality, allowing them to thrive where native species cannot.
- reproduce rapidly, enabling populations to establish and expand quickly.
- Goldfish can spawn three times a year (500-1,000 eggs each time) and can reproduce by gynogenesis (without a male).
For these reasons, once identified in a body of water, it is important to take the necessary action to remove invasive goldfish.
Next steps
The piscicide (a pesticide specifically for fish) Rotenone has become the standard eradication tool for invasive goldfish, as various Alberta municipalities have shown limited success using methods such electrofishing, netting, and trapping. This is because:
- Rotenone is a naturally derived plant compound that selectively impacts organisms that breathe through gills. It does not pose a risk to humans, birds, mammals, or pets when properly applied.
- While all dead fish will be appropriately collected and disposed of, the consumption of treated fish is not harmful to wildlife.
- Rotenone breaks down naturally within one to two weeks depending on water temperature and sunlight hours.
The City has engaged a consulting firm with extensive experience to lead the Easton SWMF goldfish response using Rotenone, starting the second week of September.
A second application will happen approximately three weeks later.
Fish eggs are not susceptible to Rotenone and typically hatch within one week. Because of this, two Rotenone applications are typical to ensure all eggs and resulting hatchlings are eradicated.
Specific dates will be updated here closer to the time, with additional notifications made directly to residents in the Easton area.
What to expect:
- Areas around Easton SWMF will be sectioned off with construction fencing from approximately Sept. 1 to Oct. 14. Once exact dates are determined, they will be updated here.
- Residents can expect to see staff wearing personal protection equipment while working on a small boat and along the shoreline.
- A faint mothball smell might occur during application periods.
- A City staff member will be on site at the Easton SWMF to answer any questions during the application process.
Frequently asked questions
Background
Stormwater management facilities (SWMF) are not naturally occurring waterbodies. In urban centres, hard surfaces like sidewalks, roads and rooftops prevent stormwater from soaking into the ground.
Although SWMFs appear to be ponds, they are engineered infrastructure designed to collect rain, snowmelt, and other contaminants such as oils and road salts that enter the storm sewer system. From there, the runoff flows through the stormwater facility, and cleaner water is gradually added through outlet structures.
Click here for more information about the City’s stormwater management system.
Most invasive goldfish are common aquarium pets that get released into waterways.
Goldfish have been found in over a hundred locations throughout Alberta, mainly in urban stormwater management facilities. Due to the continued release of aquarium fish into the wild, more locations are found each year.
Yes. Introducing a fish into any waterbody other than where it was found, can lead to fines of up to $100,000 and/or a year in prison.
Once in the wild, goldfish can tolerate vast water temperatures and low oxygen levels, easily outcompeting native species. They can carry parasites and diseases. Goldfish prey on native fish eggs, snails and plants and their feeding habits stir up sediment increasing water turbidity.
The Response
On May 5, 2026, two fish suspected of being goldfish were collected from the Easton SWMF. DNA testing performed by the University of Alberta confirmed these to be goldfish. The City immediately began consultations with AEPA, other municipalities and subject matter experts, to assess and manage the issue.
Goldfish are prolific and populations can grow rapidly. The potential for movement or transfer between waterbodies is relatively high and made worse by heavy rainfall and flood events.
In response to the initial discovery, staff implemented several immediate actions including:
- installation of outlet screens to reduce fish movement through the storm system
- enhanced trapping and surveillance efforts
- ground based inspections, boat surveys, cameras, and visual observations
- engagement with AEPA, neighbouring municipalities, and consultants
- collection of eDNA samples
Prevention is the best defense. However, once goldfish become established, Rotenone is the most effective and reliable method for completely eradicating the population and preventing its spread.
Treatment
Rotenone is a naturally occurring compound that is derived from the roots of a tropical plant from the bean family. Alberta Environment and Parks use the commercially available Rotenone formulation called Prentox Nusyn-Noxfish Fish Toxicant. It is a registered pesticide with the federal Pesticide Management Regulatory Agency (PMRA).
Rotenone provides the highest likelihood of eradication. Several Alberta municipalities have tried alternative methods with limited success. Rotenone was recommended by AEPA, other municipalities and subject matter experts.
Yes! The City’s contracted firm has completed a total of 32 Rotenone applications for eight municipalities.
Rotenone application itself takes approximately one day. Clean-up and monitoring will continue for a few weeks following the first treatment, until a second application. Residents will notice signage and barricades/fencing up to one week prior to the treatment and two weeks following the second treatment.
Safety
No, it is not. A 132-pound person would have to consume more than 150,000 litres of Rotenone-treated water within a 24-hour period to receive a lethal dose. There is no opportunity for long-term effects since Rotenone biodegrades within two to four weeks. The use of Rotenone for fish eradication does not present a risk of adverse effects to humans or the environment.
Certified applicators are handling concentrated product which poses a larger risk of exposure. When applied, the product is diluted and generally applied below the surface of the water, reducing the risk to the surrounding area and individuals.
Wells and groundwater will not be impacted by the Rotenone treatment. Monitoring studies show that groundwater in adjacent areas have not been affected.
No. Fish are more susceptible. All animals have natural enzymes in the digestive tract that neutralize Rotenone. However, fish and some forms of amphibians and aquatic invertebrates are more susceptible because they are gill breathing animals. Their digestive enzymes cannot neutralize Rotenone. Rotenone treatment is being specifically planned for the fall when amphibian impacted is minimized.
For reasons listed above, birds and mammals that eat dead fish and drink treated water will not be affected.
Residents may notice:
- Partial closure of some areas of the Easton SWMF for up to six weeks.
- Minor chemical odours that smell like mothballs for one to two days.
- Temporary changes in water colour.
- Appearance of dead fish for one to two weeks.
- City and contractor staff in or around the area monitoring it for approximately six weeks.
For more information about Rotenone, please view this fact sheet from the Government of Alberta.