Cold Weather Fish Care

During a Power Failure
If the power goes out, your aquarium will lose three important elements: heat, air (from lack of water movement), and filtration. Initially the tank is not in immediate danger. However, if the power is not back in twenty to thirty minutes, assume the worst and take steps accordingly.

Maintain Heat
Jot down the initial water temperature, so you have a yardstick to go by. Fill the plastic container or zip lock bag with hot tap water, then seal it and place it in the aquarium. Even though your water heater no longer has power, the water will still be warm enough at this point to be of benefit.

To retain as much of the heat as possible, wrap the tank with thick towels or heavy blankets. Use rope or sturdy tape to secure them as closely as you can against all sides of the tank. Lay at least one blanket over the top of the tank.

Aerate Water
Place a battery-operated aerator in the tank to keep the water moving while the filter is off. You can purchase aerators at a pet shop or even a bait shop. If you have more than one tank, rotate the aerator for ten minutes at a time in each tank. If you do not have an aerator, and the power is out for more than an hour, you'll have to hand aerate the water. Use the small plastic container to remove a cup or two of water, then hold it well above the water level and pour it back in (the idea is to agitate the surface of the water when doing this). Repeat this process for five minutes out of each hour.

Now all you can do is wait for the power to come back on. Do not feed the fish during the outage. It will cause them to produce more waste, which cannot be eliminated readily without the filter running. If the power is out more than two hours, remove the filter media from the filter unit. Otherwise it will pollute the tank with dead bacteria when the power comes back on.

Monitor the water temperature, and continue aerating the tank. In the event a fish dies suddenly, remove the body immediately so it does not impact the biology of the tank. As the temperature continues to fall, remove the container holding hot water and refresh it with hot tap water. The water in your insulated water heater will stay hot for many hours. If your tap water is no longer hot, seal a hand-warming unit in the container and place it in the tank.