We have a battery-powered airstone for such things.  You can get them at many pet stores or pet departments.  If it's not going to be out for too long, I wouldn't worry, but if we're talking at least half a day or more, I'd look into getting an airstone for them.  That should last them till the power lines are fixed.

Well, if the power would be gone for long, I'd perform a water change, that would introduce more oxygen into the tank and remove some waste Otherwise, the airstone is a brilliant idea!

Oh, that long?
In that case you'd better have the test kit ready and change the water pretty often, unless you find the generator

I'd say for over a day, water change and battery powered airstone.

That's so sad about your fish.

I'm happy to say that my fish made it thru ok.  Our power was out for 1 1/2 days, which was good compared to the other neighborhoods nearby.  Some people went a full week with no power.  My internet was out for 1 1/2 weeks.  ugh.  I'm so glad this happened before we hit the 95-100 degree weather.

On day 2 of the power outage I confirmed with my village that the tap water was safe to drink, and since it was, I did a water change like you all recommended.

I have verified that when the power goes out the quality of your tap water could be bad, so that's something to confirm before doing water changes.

Since I had no electric, and no internet, and my Android was not charged, and my car phone charger wasn't charging the phone, and the gas stations were all closed... it was so hard to do any internet research on battery powered air stones, etc.  What I've found out so far is that the batteries only last for a short while, not days, and that they don't have any that would be strong enough for a 75 gallon tank.  At least that's what the guy on the phone told me.

I'm still going to do more research now for something battery powered that will work for me, BEFORE it happens again.  

Thanks for all the advice!!