Can I Cover My Fish Tank with a Towel at Night? Tips and Considerations

Many aquarium owners wonder if it is safe to cover their fish tanks with a towel at night.

While it may seem like a good idea to reduce light and noise in the tank, covering it with a towel can pose some risks to your aquatic creatures.

When you cover your fish tank with a towel, it can darken the enclosure, which can cause your fish to become stressed. It can also lead to a lack of oxygen, which could endanger your aquatic species. 

Covering your fish tank with a towel can also trap heat and humidity, which can cause the water temperature to rise and lead to the growth of harmful bacteria and algae. This can be especially dangerous in warm weather or if your tank is already prone to algae growth.

Therefore, it is generally not recommended to cover your fish tank with a towel at night. Instead, consider other methods to reduce light and noise in the tank, such as using a dimmer switch on your aquarium light or placing the tank in a quieter room.

Factors to Consider

When deciding whether to cover a fish tank with a towel at night, there are several factors to consider. These include oxygen levels, light exposure, and temperature control.

Oxygen Levels

One of the main concerns when covering a fish tank with a towel is the reduction in oxygen levels. 

Fish require oxygen to survive, and a lack of oxygen can be fatal. If the towel covers the entire surface of the tank, it can prevent oxygen from entering the water.

This can lead to a buildup of carbon dioxide and a decrease in oxygen levels, which can harm the fish.

To prevent this, make sure the towel is not completely obscuring the tank. Leave a small gap to allow air to circulate. Another option is to use a mesh or net cover, which still provides some protection while allowing air to circulate freely.

Light Exposure

Fish require periods of darkness to rest and avoid predators. Covering the tank with a towel can provide this darkness.

But it is important to consider the amount of light exposure the tank receives during the day. If the tank is located in a room with natural light, covering it with a towel at night may not be necessary.

Alternatively, if the aquarium is kept in an artificially lit room, covering it with a towel at night can simulate a more natural day/night cycle for the fish. In doing so, you can aid in the control of their behavior and the promotion of healthy development.

Temperature Control

Covering a fish tank with a towel can also help regulate the temperature of the water. This is particularly important in colder climates, where the temperature can drop significantly at night. 

The aquarium heater generates heat, and if the tank is covered, some of that heat will be trapped inside, where it can help maintain a consistent temperature for the fish.

However, it is important to monitor the temperature of the tank regularly, especially if the towel covers the entire surface of the tank. If the temperature becomes too high, it can harm the fish. 

It is also important to ensure that the towel does not block the filter or other equipment, as this can disrupt the water flow and harm the fish.

Alternative Fish Tank Covers

While towels can be used to cover fish tanks, there are other more suitable options that can provide better protection for the fish and the tank.

Glass or Polycarbonate Lids

One option is to use a glass or polycarbonate lid that can be purchased from a local fish store or online. 

These lids are durable and can cover the entire tank, including the lighting fixture. They are also easy to clean and maintain.

Plastic Lids

Plastic lids are another option that can be used to cover the top of the aquarium. They are less expensive than glass or polycarbonate lids but can come with some drawbacks. 

For example, they can warp over time due to heat from the lighting fixture, and they may not fit as snugly as glass or polycarbonate lids.

Screen Netting

Screen netting is a practical and useful option for those who want to prevent fish from jumping out of the tank. 

It can also be used to cover bird cages, hen coops, and other enclosures. The clear mesh netting is made of nylon and can be cut to fit the size of the tank. However, it does not provide insulation or protection from dust or debris.

DIY Covers

For those who enjoy DIY projects, there are many options for creating custom fish tank covers. Some people use plexiglass or acrylic sheets to create a custom lid that fits their tank perfectly. 

Others use materials like egg crate lighting diffusers or plastic canvas to create a cover that allows light to penetrate while still providing protection for the fish.


Fish keepers may have differing opinions on whether or not to cover their tanks with towels at night. However, the general consensus is that it is not recommended to cover a fish tank with a towel at night.

While a towel covering the tank can darken the environment, it can also cause a lack of oxygen in the water, which can harm or even kill the fish. When the tank is covered, harmful chemicals like carbon dioxide can accumulate in the water.

Overall, it is recommended to avoid covering a fish tank with a towel at night. Instead, consider other options such as turning off the tank’s light or using a dimmer switch to create a more natural day/night cycle for the fish.

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