How Do Fish Tanks Increase Humidity?

If you are a pet fish lover, and you have an aquarium, you might ask; Does a fish tank act as a humidifier?

Anything that contains water can be a natural humidifier. When the water starts to evaporate, it will increase the humidity in the room. In another article, we saw how a water bowl can increase humidity.

So, do fish tanks increase humidity, and can you rely on them fully? A fish tank will evaporate, and this evaporation increases the indoor humidity of the room where you set it. The right humidity for your home should be between 40 and 55%. If the aquarium increases the humidity to more than this, use covers to contain the evaporation.

The most important thing is to keep an eye on your indoor humidity. If it rises too much, it could destroy your paint, furniture, books, and other items. Too much humidity can also cause mold to grow in dark spaces.

How fish tanks increase indoor humidity 

Image of can a fish tank increase humidity

So now we agree that fish tanks increase indoor humidity. Using an aquarium is one of the ways to increase indoor humidity naturally, that is, without using a humidifier.

Fish tanks raise humidity by evaporation

A fish tank increases humidity through evaporation. When the heat tank is subjected to even minimal heat in the air, evaporation must occur. This is what keeps the room humidified.

In fact, in some cases, you might have to get a dehumidifier to use in the same room that has the fish tank.

But if you live in a place that has dry air, such as Nevada, you will be grateful for having an aquarium in your room. It will increase the humidity in the air and help you sleep better.

Evaporation is part of the cycle of a fish aquarium. Thus, if you close the windows to keep the dry air outside, the aquarium might be enough. If it is a big aquarium, you can even open the doorways so that the same vapor finds its way into other rooms.

So yes, to the question of: does an aquarium act as a humidifier. The answer is a loud yes. Do use a hygrometer to find out the humidity level in your home at all times.

It will help you to know whether to buy a humidifier or a dehumidifier to use in the same room that has the aquarium.

A fish tank humidifier is so effective. It can even increase your indoor humidity too much. Thus, check the windows for condensation. If you notice this, you need a dehumidifier.

Rate of evaporation

Image of how to use a fish tank to increase humidity
When water in a fish tank evaporates, it increases the humidity

An aquarium to act as a humidifier is such a good idea. However, if the air in your place gets dry, you need to know whether you should buy a humidifier. Perhaps you can just rely on the aquarium humidifier, but you cannot be sure.

There is simply no way to find out whether the fish tank humidifier evaporation will be enough to humidify your indoor air.

Some people say that their tanks evaporate about 2 inches of water a week. This is enough evaporation for a room. However, to dissipate the humidity, you would need to have a small fan close to the tank to whip the humidity around.

At the same time, the fan will also bring more dry air to the surface of the water, making it evaporate some more.

In summer, the rate of evaporation is quite high, since it can be up to 5 inches in a week. Thus, you have to top up the water often.

In the room with your fish tank humidifier, you will need a dehumidifier in summer to lower the level of humidity.

There is much more related to aquarium humidifiers. Here are just a few of them:

Do fish tanks cause mold?

Yes, fish tanks can cause mold. As we have already seen here, fish tanks increase the level of humidity from evaporation.

Thus, if the evaporation is contained in one small room, the level of humidity can rise to 80% or more. This could cause the proliferation of mold under things, in dark corners, and so on.

How do I control the humidity in my fish room?

To control humidity in the fish room, first, you need a hygrometer so that you can know when the humidity is taking a dip or increasing too much

Also, you can learn a few things from the fish room humidity. For instance, if the humidity is too high, it could mean that the water is too warm, and this could affect your fish.

Image of do you need humidifier in fish tank room

Remember, warm water will have less oxygen. Thus, it could affect the fish negatively by making them sluggish. They will not feed well, too.

If you find too much condensation on the windows, check the warmth of the water so that you do not affect your fish.

Where should a fish tank be placed in a room?

First, you should place the fish tank in a place with plenty of light but away from direct sunlight.

If you particularly want to increase the humidity in the room using the aquarium humidifier, place it in such a place that it can spread vapor throughout the entire room. Of course, you can always add a fan to help spread the vapor around the room.


Yes, a fish will act as a humidifier. If you have one, it is a perfect alternative to a humidifier. The same way you can have a charcoal DIY dehumidifier, the fish tank will help.

The fish tank will raise the humidity level by evaporation. If you don’t have one or a humidifier, you can use other natural ways to humidify a room.

You can also help by using a small fan to help spread the vapor into the room. Depending on the size of the fish tank, it might be all the humidifiers that you will need.

To control fish tank humidity in summer, you should probably cover it so that it does not evaporate too much. You can also keep adding cold water to keep the evaporation down.