This is the first case of whirling disease in Canada.
Caused by the microscopic parasite Myxobolus cerebralis, infected fish swim in a whirling pattern.
Parks Canada has restricted access to Johnson Lake and prohibited water based recreational activities at the lake to reduce the risk of further spread of the disease.
Sampling and testing of fish from other water bodies in Banff National Park is underway.
In other news, the Scottish Aquaculture Innovation Centre (SAIC) is investing nearly £250,000 in two projects that aim to improve biodiversity and fish health in aquaculture through creating new diagnostic tools.
One project led by Kames Fish Farming Ltd in partnership with the University of the West of Scotland, Marine Harvest, Randox Food Diagnostics and Europharma, aims to create a method of assessing fish health with earlier and more specific diagnoses that reduces veterinary requirements and shortens the diagnostic period – which is typically seven days or more.
The other looks at a more efficient method for monitoring the diversity of organisms living in the seabed around fish cages, and is led by Marine Harvest Scotland partnering with the Scottish Association for Marine Sciences (SAMS), UHI Inverness College, Rivers and Lochs Institute and the Scottish Environmental Agency (SEPA).