How To Heat an Aquarium Without a Heater

Heating an aquarium, especially during cold winter months with a power outage can be incredibly challenging. Winters can be brutal, and cold can creep into older and poorly insulated homes very quickly. Although many fish have a fair amount of temperature tolerances, it’s important to have a plan ready in case the temperatures drop below that threshold.

Besides power outages, having dozens of aquariums running individual heaters can be expensive. You use up a lot of outlets, spend money on replacements, and risk purchasing a faulty heater which can ruin a fish tank. Warming an aquarium in different ways might be a better option. This guide will discuss many options to warm your aquarium during power outages and a recommended method to warm multiple aquariums to help lower those high electricity bills.

Heating the Room

A room with many fish tanks is called a fish room, and heating a fish room is often cheaper than heating individual fish tanks. If you have a room completely devoted to your fish tank hobby, it might be time to toss the aquarium heaters and switch to something that will heat the whole room instead. Heating the room instead of individually heating aquariums has a few perks:

  • Cost saving
  • Heaters won’t break in your aquarium
  • No more heater replacement
  • Saves outlet space

I have dug around to see the best way to heat a fish room. Many aquarists suggest using an Oil Filled Radiator Heater, such as the PELONIS Oil Filled Radiator Heater. As a bonus, I would recommend also using a fan, like the Genesis 20″ Box Fan, on a low setting to help disperse the heat around the room. You’ll want to choose the heater and fan that is appropriate for your room’s size.

The reason many fishkeepers enjoy using this type of heater is that it uses less electricity compared to a space heater, and also doesn’t get as hot, which lowers the chance of it causing a fire. You’ll have to look to see whether your heaters use more electricity compared to the Oil Filled Radiator Heater before deciding whether this switch makes sense.

Add a Well-Fitted Lid

Equipment such as hang on back filters, circulation pumps, and lights create heat as a byproduct while working that will warm your fish tank. A lot of heat from water is lost at the surface. Something as simple as adding an aquarium glass top can help warm a fish tank. When you add a lid to your aquarium, you are essentially creating a barrier between warm fish tank water and cool ambient air. It takes longer to alter temperature through glass than a large opening such as the top of a fish tank.

This method isn’t ideal, because you may not reach a desired aquarium temperature, and you might not have enough equipment running to warm the fish tank. Also, keeping a stable temperature will be impossible because you’re ideally at the whim of the ambient temperature and whatever equipment you have running. There are a lot of glass top options on Amazon, you’ll just have to match the available options with the dimensions of your fish tank.

How To Heat Aquarium During Power Outage

If you’re stuck in a power outage and do not have a way to warm your aquarium, there are a few things you can do to help your fish tank when your heater is out of commission. These are temporary solutions that can provide relief for your slowly cooling aquarium. You can try one method or both to help keep your aquarium warm.

Wrapping a Blanket Around Your Aquarium

If your power is out, and the temperature in your home is slowly dropping, you may be worried that your fish tank temperature will also drop to dangerous levels. A temporary but quick solution is to wrap your aquarium with a blanket. The blanket will help insulate your fish tank for some time while you wait for the power to return. Besides a blanket, you can use styrofoam or something like FOAMULAR insulation to temporarily protect your aquarium from the cold. Styrofoam and FOAMULAR are great at keeping heat in and cold out.

Heating Aquarium With Water Bottles

You can likely boil some water if you have access to a gas stove during power outages. In a pinch, you can boil some water, place the hot water into a plastic bottle, or a bottle with a secure lid, and place that into the aquarium. The water will slowly release the heat into the aquarium. You can repeat this process until the power comes back on. If you have a small fish tank, keep an eye on your aquarium’s thermometer so the temperature doesn’t get too warm. I recommend a battery-operated air pump, like the AquaMiracle Battery Powered Aquarium Air Pump, to help move the water around as well as provide much-needed oxygen to your fish for elongated power outages.

Keep Cool Water Fish

If you’re not attempting to warm your aquarium but instead are trying to avoid using a heater but still want to keep fish in an aquarium, consider purchasing cool water fish. Many different species of fish will do great in colder water. Goldfish and White Cloud Mountain Minnows are just two of many different species that are great options. Regardless of what you decide to keep, it’s important to research their preferred habitat type, tank mate compatibility, aquarium sizing needs, and other husbandry requirements before purchasing them.

Final Notes

There are many different options to warm your fish tank without a heater. Unfortunately, most of these options are only temporary solutions for very short periods. If you want to rid yourself of your heater altogether, you’ll have to consider cool water fish or other cold water-loving animals to keep in your aquarium. Check out the 6 Best Aquarium Heaters for Freshwater & Saltwater Fish Tanks if your heater is on its last legs or has recently broken. If you have your own method for keeping your aquarium warm, let me know!