How to protect your fish during power failure

This is a copy originally posted by Star:

If you experience a power cut for just a short time there is usually no need to panic, most tanks will be fine without power for an hour depending of course on room temperature.

Keeping a tropical tank warm
Wrap the tank in bubble wrap, blankets or duvet to keep as much heat in as possible taking particular car to cover the hood/lid, leave a small gap so you can see your thermometer. If the tank temperature starts to fall you can fill a plastic pop bottle with hot water and place the bottle into the tank, this will help keep the tank warm.

Air/water circulation
This is more difficult. If the area you live in has frequent power cuts it maybe worth investing in some battery operated air pumps (available on e-bay and good fishing tackle shops) These will last, depending on the quality of the battery, around 8 hours. Do not be tempted to blow air into the tank by mouth, this will be harmful to the fish.

Filter
Caring for your filter in a power cut is the most important. If the power is not back on within 1 hour, remove the sponges from the filter, wash them out a little in tank water (as you would for normal cleaning) and put the sponges directly into the aquarium. The bacteria require oxygen which is can get from the water and remain ok, if left in an external filter the oxygen will quickly deplete. If left in the filter toxins can start to build up which will be released into the tank.

Do not feed your fish during a long power cut, this will help keep the waste they produce down and help with the water quality. If you are able to warm some water you can do small water changes and siphon waste from the bottom. Fish can go without being fed for a number of weeks so a few days they should be ok.

Once power has returned
Put all sponges back into your filter and re-fill making sure your outlet pipe is placed into a bucket directly or connect a hose to the pipe so the first load of water does not go into the tank. Then you can set it back in normal motion. Keep a check on your water stats for the next couple of weeks to ensure you have no spikes of ammonia or nitrite with the filter being "down" If your tank temperature dropped a couple of degrees let the heater warm the tank back up gradually, do not be tempted to add hot water to bring the temperature back up. Most fish will have coped with the drop fine and will be fine with the temperature going back up.

Feeding
If your tank temperature dropped and the fish appear sluggish, do not feed until the temperature has returned to normal and the fish back to being their active selves. Feed some treat foods such as bloodworm or brine shrimp & garlic to kick start their appetite and help boost their immune system.