Keeping fish alive through an Alberta winter power outage

Short answer: in a winter outage the two things that threaten your fish are loss of oxygen and falling temperature — and a tank holds heat longer than most people expect. Your priorities, in order: keep the water oxygenated with a battery air pump, slow heat loss by wrapping the tank in blankets and keeping the lid closed, and stop feeding. Most tanks ride out a short outage without drama. For a longer one, insulate hard, keep air moving, and warm the water gently rather than all at once. A little preparation now is what makes the difference on the night.

What actually threatens the tank

When the power drops, your filter and heater both stop. The most urgent loss is usually oxygen and water movement: a still tank stops exchanging gas at the surface, and in a stocked tank oxygen falls before temperature becomes critical. Temperature matters too, but a reasonable body of water cools slowly — you often have several hours before it becomes a real problem, and that time is what you are protecting.

Have a battery air pump ready before you need it

The single most useful item in an outage is a battery-powered air pump. It keeps the surface moving and oxygen coming in when nothing else is running, and it costs little to keep in a drawer with fresh batteries. Our Marina Battery Air Pump is made for exactly this; pair it with an air stone from the aeration collection. Buy it now, not during the storm — that is the whole point.

Insulate to hold the heat you have

Every degree you keep is a degree you do not have to add back:

• Keep the lid closed and wrap the tank in blankets, towels or foam — sides first, then the top, leaving room for the air line.
• Move the room's warmth toward the tank if you can, and keep doors to cold rooms shut.
• A thermometer such as the Marina LCD Thermometer lets you watch the trend without opening anything up.

Stop feeding

Do not feed during an outage. Digestion uses oxygen and uneaten food fouls the water — both are the last things you want when the filter is off. Fish are fine going without food for days; a well-meant meal is a genuine risk here, not a kindness.

For a longer outage

If the power is out for many hours, warm the water gently — sealed bottles or jugs of warm (not hot) water floated in the tank, or small amounts of dechlorinated warm water added slowly, aiming to hold temperature rather than chase it up quickly. Keep the air pump going the whole time. If you have a canister or hang-on-back filter that has been off for hours, do not just switch it back on cold without checking it — stagnant filter water can foul a tank on restart.

When the power comes back

Turn the filter and heater back on and let temperature recover slowly — do not perform a big cold water change straight away. Watch the fish for a day or two, and test the water once things are running. If the heater took a knock, browse replacements in heaters, and size the new one with our heater sizing guide.

Living with Alberta winters, a battery air pump and a couple of blankets set aside is cheap insurance. If you are still setting up your tank, your first aquarium covers the gear worth having on hand.

Written by the team at Tropical Fish Imports in Lethbridge, Alberta. Last reviewed August 2026.

Want to put together a small outage kit for your tank? We can help you pick the right battery pump and backup gear — visit the shop, call 403-380-4506, or send us an email.