I've kept comets in a 75g with an Oscar and they did fine. Water temps were at 80 degrees and the fish adapted and looked fine for months. Happy, swimming, eating, growing. On the flip side 90% of the goldfish I've kept (Comets and shubunkins and some koi) have been in in aquariums and/or outdoor ponds with the water below 70 I'm assuming. Again, they put on great size, are very active, and seem extremely happy and non stressed. I can feed them from a foot away and I'm working on them eating out of my hand. So really what's the definition of thriving? Not sure about that article