The Guide to Eating Ontario Fish is an advisory database that provides fish consumption advisories for Ontario lakes and rivers. The zip file includes a GIS shapefile of all lake/river locations and a text file of all consumption advisory data from the current edition of the Guide.

https://www.ontario.ca/data/guide-eating-ontario-fish-advisory-database

The Government Of Ontario also publishes a map guide to eating Ontario fish:

https://www.ontario.ca/environment-and-energy/eating-ontario-fish