Okay, so for us Betta lovers, no lower than about 65. Question: why would you not feed while the power is out? Is that for Bettas only, tropical fish only, or all denizens of the aquarium? Is it something about aeration?
My condolences to your wife about her Betta, charliebankston.
I noticed that within 10 minutes of the electricity quitting my snails made a beeline--er, snailine--to the heater, which they hugged for the duration trying to absorb as much residual warmth as possible. They stayed stuck to it until the tank was back up to 78-80.