I was afraid you would ask that....
I don't remember exactly. My guess would be probably no lower than
~14-15oC though I wouldn't bet my life on it. Once the sun hit the room
in the winter time for ~20 minutes air temperature would pretty quickly
hit ~25oC or so. A lot will depend upon the aspect of the room relative
to the sun in the winter versus summer. I doubt there isn't a rainbow
that wouldn't be ok at 15oC although several don't like it at 13oC.
Typically the Aussie fish have broader cold and warm tolerance than their
northern counterparts. You won't get much growth and maybe colour at
those temps, but then you won't need to feed them as much which means they
don't poo as much and hence there is less need to change water. Plus, if
it is likely to get cold you can put a little heater in the room on a
timer. If you are really worried about temperature during the winter and
you only have a few tanks I'd drop a heater set to 18oC in them.
I had mostly fish like Mogurndas, the various fishes from Dalhousie
Springs, a couple different desert goby species, some eel tailed catfish
and a few other odds and ends and probably a couple of rainbows.
The only problem with having a polycarbonate roof, aside from getting too
hot in summer and costing a few $$ is that with all the light algal
problems can be a hassle. I was too lazy to shade mine so I had lots of
algae.
Cheers
Peter J Unmack peter.unmack at asu.edu
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DESERT FISHES RULE: To boldly thrive where no other fish can make it!
Australian desert fishes pages at http://ozdesertfish.base.org (don't
forget to visit the Desert Fishes Council pages too)
Native Fish Australia pages at http://www.nativefish.asn.au
North American Native Fishes Association at http://www.nanfa.org
Aquatic Conservation Network at http://www.acn.ca