Let us observe a moment of silence for all the tanks on the East coast that were left without heating and filtration due to the power outages due to Frankenstorm Sandy.
Here’s a summary of what can be done to minimise damage that comes with the loss of electricity, and how save precious lives: that of your fish and your bacteria.
1) Remove the glass or other tops for aeriation
2) Unplug all electrical equipment connected to the aquarium
3) Open up all canister filters to expose the water and media inside, to at least a bit of air and oxygen
4) Install improvised, battery powered sponge filters if you can
5) Try to control temperature with increasing ambient (room) temperature, if you can, or add warm water periodically, if your system produces that (and you are sure that the tap water is still healthy)
6) When power does return, be careful to heat up the aquarium very slowly, otherwise the fish will die.
7) Pray diligently