They say it might seem a humane way to dispose of unwanted fish, but it is hurting local species and ecosystems.
Kate Wilson, an aquatic invasive species specialist, says both fish and the water from aquariums can have diseases and parasites.
She also says domestic fish will compete with native species for food and eat fish eggs.
She says goldfish and Prussian Carp, both of which are growing to be massive sizes in Alberta bodies of water, are being found across the province.
She says dumping fish is illegal and can result in a fine of up to $100,000.
Wilson says the fish they are finding aren’t likely ones that have been flushed down the toilet.
“A fish wouldn’t survive being flushed through the water treatment system, but those diseases and parasites that we talked about could potentially survive the process and end up being discharged into rivers and lakes,” explains Wilson. “We are not advocating that even dead fish be flushed.”