How to Keep Fish Water Warm Without a Heater

Previously I have discussed the use of heaters for aquariums in previous articles. If you haven’t read the article, maybe you should read the article first and then return to this article.

Basically, heating an aquarium without a heater is not an easy thing to do, or even impossible if you want to warm an aquarium forever without a heater. If you really want to warm the aquarium in the long term, you should really use a heater .

Because in this article I will share information on how to warm an aquarium without a heater when in an emergency or power failure. I myself have never used a heater because it is not needed for the fish I keep.

Use the lamp as a heater

If you really have a plan not to use a heater and still want to warm the aquarium, one way is to use lights. Lamps for aquarium lighting produce heat energy so this energy can also be used to warm the aquarium.

Of course this heat energy is not high and probably will not be enough to warm the water in the aquarium. Another combination that can be tried is to provide an aquarium cover. With a cover above the aquarium, it not only serves to reduce evaporation and dispel jumping fish, but also can maintain the temperature in the aquarium.

Another way is to use a dip lamp. This type of lamp can be placed in the water so that the distance is closer to the water and the heat energy is instantly dispersed. However, you must know that the use of this lamp cannot be done 24 hours because fish also need to sleep at night. Therefore, the use of lighting should follow the original nature.

That way the use of lights as heating may indeed be possible during the day, but at night these lights must be turned off so that the fish get rest and are not stressed because they never see at night because the lights are constantly on.

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Take advantage of the sun

With the same concept as using heat from the light produced by a lamp, direct sunlight can be used to warm the aquarium. Of course, if exposed to direct sunlight, the water temperature will slowly rise, but this increase cannot be predicted by how much.

Chances are the water is getting too hot for the fish which can be dangerous. In addition, another possibility is that there will be excess algae growth when the aquarium is exposed to direct sunlight.

When the aquarium is exposed to sunlight, of course, it can’t be all day. For example, my room will be exposed to sunlight from morning until around 11 pm because at that time the sun is already above and not in the east.

After that there will be no direct sunlight that will enter the room. If it is like this, the aquarium temperature will certainly change again because it is not exposed to light anymore. In fact, the temperature will drop even more at night because there is definitely no sun and the nights will be colder.

This way the temperature in the aquarium will change at any time because it depends on sunlight alone. This situation can actually make the fish become stressed because of changes in temperature that occur too often.

Use warm water

Using warm water and placing it in a container is another way to warm the aquarium water. Because this method is quite inconvenient, this method is only effective for a short period of time, for example due to a power outage, or the heater is damaged and has to wait for a new heater to arrive.

The trick is to make warm water and then place it in a container, this container can be like a drinking bottle or other container that is heat resistant and safe for the aquarium. Do not immediately add hot water to the tank, this will cause a rapid rise in temperature and shock the fish.

After being placed in a container that is safe and does not leak, then the container is placed in the aquarium and allowed to float to circulate heat energy into the aquarium. Of course you have to pay attention to this container so that the fish don’t come close and get hot or pinched.

In addition, the movement of temperature must also be considered so that there is no sharp increase. The troublesome thing is, this has to be done over and over again until the electricity is back on or a new heater.

retain heat

Maintaining heat in the aquarium is also very important because for a while it can’t generate heat whether it’s due to a power failure or a broken heater . This method can be done to complete the method of heating the aquarium in the previous way, of course this is also only an emergency measure.

How to maintain heat that can be done is to cover or wrap the aquarium with a towel or old newspaper. The top of the aquarium can also be covered so as to minimize the release of heat from the aquarium. If this method is combined with the other methods above, chances are the aquarium can keep the temperature from dropping too far in an emergency.


In essence, if you really aim to heat the aquarium, you should immediately use a heater because there is no other safe way to warm the aquarium. Using light from a lamp or direct sunlight is not a safe option in the long run. Because it causes the possibility of other problems such as algae and temperature changes that are too frequent.

Another case if in an emergency due to a power failure or a broken heater . If this happens, then you can take some emergency measures to prevent the water temperature from dropping drastically.