If native bullheads aren't legal to keep then how about Ameiurus brunneus, Ameiurus platycephalus, or Ameiurus serracanthus which are all native to only the southern US and nowhere near western Canada. They can all tolerate lower water temps.
Nice fish but good luck trying to find any Australian cats either in the US or Canada. Tandans are one of my dream catfish but dang they're impossible to get ahold of.
There is at least one Asian Bagrid species that can tolerate cool water, Tachysurus Fulvidraco. Probably hard to find locally as I'd only found them once and bought 5 of 'em. A couple of years later when full grown, largest 13", I sold 3 to a guy who wanted them for his outdoor pond here in SoCal. He sent me a message the following spring that the fish had survived the winter in his pond. At the very least the pond temp would have likely been in the 50-60 degree ranges during the winter here .
A Pic..