I suppose it all depends on what fish you have .... & how big a tank, etc.
I've not have to deal with a power outage, but people on this forum had reported doing the following during prolonged power outages:
1. keep the temp up by wraping the tank in a blanklet, and doing water change with warm water <that's assuming you can make hot water with somekind of heater> ... This was from one of us in Canada when a tank will turn into a big icecube with power out at this time of year ... You prob won't have to worry about that in Huston
2. keep up aeration by making waves in tank <best way - a battery powered airpump ... I supposed you can do the same with a stick or something>, if you have a
HOB filter, you can take a cup & manually move water through the filter every so often ... This will keep your filter bugs alive. ... just keep the filter wet.
3. If you have a really long power out - like days - you might have to do water changes to keep your levels in check ...
4. If you have a canister filter, it is important to disconnect it from the tank with a prolonged power out. The bugs in the filter will die without water circulation & start to make bad stuff (like H2S) without
O2. This will get flush into the tank & possibly kill your fish when the power comes back on. For canisters, it is best to disassemble the filter & clean it out after a prolonged powerout before using it again.
5. There were also a few threads talking about using UPS from a computer to power a filter or air pump ... But the general consensus was that it won't last very long .... so the best bet is a generator if you will have frequent power out.