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
Do you consider goldfish coldwater only fish?
- Thread starter fishdat
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There's a huge difference between thriving and barely surviving... But goldfish do not discriminate any water temperatures. That's why they are highly adaptable creatures and they're also one of the invasive species. Goldfish are thriving in cold trout lakes to the hot & polluted ponds in metro areas. Not just survive, but thriving....
Interesting read. Just as Dr. Johnson, aka koivet, says there is no agreement, not in this thread either 
Simpler goldfish spp appear to indeed thrive in almost any condition and temp if by "thrive" we mean be apparently stress-free, healthy, grow, spawn, and repeat. As for the longevity, that's where there is a cork. Indeed we lack data. IDK if proper, healthy, happy longevity is a factor in the "thriviness". We'll probably never know anyway.
Simpler goldfish spp appear to indeed thrive in almost any condition and temp if by "thrive" we mean be apparently stress-free, healthy, grow, spawn, and repeat. As for the longevity, that's where there is a cork. Indeed we lack data. IDK if proper, healthy, happy longevity is a factor in the "thriviness". We'll probably never know anyway.