shubunkin goldfish are not nearly as tolerant to tropical temps as most other fancy goldfish, as they are cold water fish. the ideal temp range for those fish is usually anywhere from 60-70 degrees so you should be fine temp wise as is. I would not really advise you keep them in a tropical tank if you want to have happy little Goldies! hope your goldfish live long and prosperous lives!
-Justin
Back in the day, it was "common knowledge" that fancies were less hardy than common goldfish in terms of surviving very cold water, i.e. under the ice on ponds. That sounded reasonable back then, especially if referring to the more extreme fancies with misshapen bodies, which already looked like they were having a hard time bumbling through life under ideal conditions.
It seems reasonable, to me at least, that the fancies are also less-tolerant of the opposite extreme of temperature; I'd bet folding money that as temperatures rise and oxygen levels drop, the globular fancies will feel the stress before a standard goldfish. They're the same species, but...
Shubunkins, when compared to things like Ryukins, Lionheads, etc. barely even qualify as fancies. They're mostly a colour morph, with perhaps slightly longer finnage, but they're still pretty close to a standard goldfish in form. Logic dictates that they would be essentially just as cold-hardy, or hardy in general, as a standard wild-form goldfish. They're all the same species.
My goldies aren't fancy, they're re-purposed feeders who just lucked out and landed a gig with a guy who doesn't use live fish as feeders. When they were small...under 2 inches...they all looked fairly long-finned and Comet-like, but as they grew most of them became less streamlined, with less elongated fins, looking just like wild fish. Oddly, a few kept their longer fins and even had them grow longer. I'm thinking that perhaps culls from fancy and semi-fancy breeding projects get tossed into the pools with the commoners and inject a bit of snooty DNA into the mix?
All of them live quite comfortably outdoors even after ice starts to form on the pond surface...and all of them live quite comfortably in the unheated basement tank that can get down to below 60F during cool snaps, and up to nearly 70F during the summer. They share that tank with Cichlasoma dimerus and Gymnogeophagus rhabdotus cichlids, Garra rufa and G. flavatra, Buenos Aires tetras, Hypostomus laplatae pleco, Corydoras paleatus cats (probably got a new name now...) i.e. a bunch of not-so-tropical fish. Everybody does well, I have the same enthusiastic bubbling mass of fish at the front of the tank when I walk up to it as seen in the pics by
Backfromthedead
and even fish that get aggressive with one another like the C.dimerus when temperatures soar in mid-summer are very peaceful and phlegmatic down at or below 70F.
The non-fancy goldies that spent the summer outdoors, with virtually no supplemental feeding done by me, grow faster and bigger and more colourful than their siblings who stayed indoors all summer, with generous feeding. Again, the indoor fish max out around 70F, while the outdoor ones can get much warmer than that during midsummer.
and they are super active, much more boisterous than i expected for a fancy type goldie. What are the limits for keeping these fish long term? Could i keep them comfortably in my tropical tank at 75-78F? And how would they fare in a community with other mid-large cyprinids like balas, tinfoils, etc.?
