There are a lot of aquarium stores in the Greater Toronto Area. I'm hoping to see them all someday.
To help with this effort, I've plotted all of the stores I've heard about on the below map (powered by Google Maps). The stores shown here are those with significant freshwater aquarium fish and/or plants since that's what I keep. For profiles and comments about the stores, check out the list maintained by the GTA Aquarium Forum.
If you know of others or know that a store has closed, leave a comment below the map. I also maintain a list of online businesses that sell aquarium plants in Canada.