I lost power for 12 hours. I do not have battery powered air pumps and all the stores were closed or inaccessible. So, I used a pitcher to take water out of the tank and dump it back in like 3 x an hour. I was ecstatic when the power went on. And I'm going to order some battery air pumps and the batterys to go with it and keep them in a safe place for the next time.
It was more stressful on me than the fish they fell asleep as soon as the light went out, meanwhile I'm looking at the clock every fifteen minutes wondering when the power is going to come back on. Let this be a lesson: preparation is key. I don't know how long it would take for the oxygen to deplete, but I was nervous as "heck."
To all of my other NE Power Grid Brothers and Sisters... I hope your situation turned out as well as mine.