If your going to let your tank temp drop down over the winter make sure it
stays close to that temp. If it starts going up and down all the time, your
goldies might get stressed out. Plus, your fish may decide it's time to make
new fish.

If you would rather not have new fish eggs in your tank, it
would be suggested to maintain the tank temp at a steady spot. I keep my
tanks in the 74-76*f range. The warmer temps help keep their immune
system at a higher level and aids in their digestion. That, and they won't
get frisky(wink, wink).