How Long Can Fish Live Without Power?

Maybe you have never experienced a power cut that lasts for hours or, in the worst cases, even for days. Even if you have, your experience could not have been as dreadful as your aquatic pets. Power cuts, in general, are quite terrifying. But understanding the fact that your pets are without light, heat, and filtration is much more horrific.

So what should you do if you face a power cut for several days? Are your lovely pets going to die?

Surprisingly, most tropical fish can live up to five days without power under a proper maintenance schedule. Certain factors are responsible for the survival of the fish during a blackout. Maintaining a steady water temperature, keeping the water oxygenated, and filtration of tank water are only a few to mention in the list.

But how are you to manage all of the maintenance details while having no electricity? Don’t be confused. This article is intended to give you all the hacks and tricks you may need when you have a power cut.

Read on to explore more.

What can happen to the aquarium during a power cut?

An aquarium is not a self-sufficient device. So you should not expect it to clean itself! It needs external cleaning and warming methods. The filter and the heater are installed to fulfil these purposes. They are solely run by electricity. If there is a power cut, the heater and filter will not function at all. 

Without the heater and the filter, your tank may not obtain the optimal temperature of the water. And the lack of proper filtration may cause excessive waste. All of these problems may deteriorate the condition of the tank, thereby killing all of the fish.

Are you scared? Don’t be. You can still save your pets. Check out the problems and preventive measures below.

Water temperature:

The water temperature is a crucial factor when it comes to the maintenance of the aquarium. Since the heater is no longer running when there is a power cut, you should maintain the optimal temperature of the water.

Water temperature

If the power cut occurs with warm water inside and the room temperature is more or less similar to that of the tank water, you should not worry. Since water absorbs the temperature of the air around, the water in the tank remains warm.

If the weather is too cold and the outage occurs for a shorter period, you should not worry. Your tank water will not get much time to release all the heat.

In case you observe a severe decrease in temperature, you will have to take all the immediate steps to obtain the optimal temperature. 

What can you do during extended outages?

You can follow specific steps to keep the temperature optimal. But there are some risks while changing the water. Sudden changes in the water temperature may shock the fish and kill them as well. You should be exceptionally careful while changing the water. 

Before changing the water temperature, you must check it. Only if you find the temperature, not at its best position you should apply the following measures:

  • You can heat up a small amount of water on the stove, grill, or any other device (which works without electricity), pour the heated water in a Tupperware container and let it float in the tank. The warm water inside the container will automatically warm up the tank water.
  • If you do not have a Tupperware container, you can mix the heated water with normal room temperature water. And carefully pour the mixed water into the tank. One thing to keep in mind is that the water should not be boiling hot. The water you add should feel cold to the touch. It is better to use a thermometer while checking the temperature.
  • If the temperature is to be lowered, you should put some ice in a ziplock bag and let it float in the water. Do not cool the water down too much if you don’t want your pets to get frostbite.


No electricity also means no filtration. Just as you can’t live in a heap of garbage, your pets would also not like to stay in a dirty tank. The extra ammonia in the fish tank may cause difficulty for your fish to survive. 

Aquarium Filtration

As in the case of the heater, you will have to apply some methods manually to sustain the tank’s condition. 

What are the measures?

You might have to siphon out the tank water frequently since your filter cannot help you in an outage. You should keep your filter media (especially the bio-wheel). Otherwise, all the good bacteria residing there will eventually die. 

You can also remove the excess ammonia from the water in order to make the water suitable for your pets.

The power cut can be seen as a golden opportunity for you to rinse and clean your filter cartridges to restore their efficiency.


The filters do another thing for us, which we don’t always think about. They oxygenate the tank water by moving it for the fish to breathe. When a power cut occurs, your pets may struggle to breathe and can even die.

Aquarium Oxygenation

This problem is not a headache for you when you have “air-gulpers” like corydoras, betta, and gouramis. They can gulp air from the air. 

What should be done?

Here, in the case of the tank water’s oxygenation, you must follow the manual methods to maintain the oxygen levels. 

You may move the water around frequently with something ‘fish-safe.’ You may use your clean hands to do so.

Removing some of the water can help you because only the top one or two inches of water hold oxygen. It becomes easier for your pets to reach the oxygen levels of the water.

You may also include a battery-powered air pump for oxygen supply.

Other measures:

You should take some other immediate steps for your pets during a power outage.

No feeding:

Believe it or not, your fish can survive without food for a couple of days. In some cases, they can even sustain for longer. 

It would help if you restrained yourself from actions that can accumulate ammonia in your tank water. If the leftover food breaks into ammonia, you are possibly doomed. You should not feed your fish for this reason.

Battery backups and portable generators:

Aquarium Battery Backup

You may invest in a battery backup or portable generators. If you want the cheap yet best option, your perfect match would be battery backups. They can power the aquarium equipment during an outage.

Always consider the amount of livestock in your aquarium before you bring any of these two. Even the weather condition of your area also plays an important role (as you do not want to run a heater in the summer season).

Need to Know:- Why do GoldFish Swim Sideways?

Final words:

In simple words, a power cut is horrible for your fish. They face many difficulties while the filters and heaters do not run. They can even die within the outage period if it is prolonged.

Just as you do not feel comfortable without electricity and an inverter, your fish might feel the same without aquarium light, heater, and filters.

But as they say, where there is a will, there is a way. With all the hacks mentioned earlier, you should be successful in saving your pets.

Is there a power cut at your place? Don’t waste time. Do take immediate steps to save your lovely pets today.

Best of luck!

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