How to Increase Oxygen in Fish Tank? (Effective Ways)

If you have a fish tank at your home and are wondering how to increase oxygen in fish tank to save your fish from suffocating then this blog post will be helpful for you. It is very important to maintain a balanced oxygen level in the fish tank, excess oxygen can also be harmful to fish. We have listed out very simple ways through which you can increase the oxygen level in your fish tank.

How to Increase Oxygen in Fish Tank (Effective Ways)

Without a proper oxygen, supply fish cannot survive no matter what you do. Well, there might be a lot of reasons due to which the dissolved oxygen level in your tank is low. We have listed out all the reasons and methods to increase oxygen in a fish tank.

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How to Increase Oxygen in Fish Tank?

Before knowing the ways to increase oxygen supply in a fish tank you should know what might be the reasons for declining oxygen in your fish tank. 

Causes of Low Oxygen Level in Fish Tank


This is one of the most common reasons for declining oxygen levels in a fish tank. The area available in a fish tank is very less as compared to a sea or river. When the population of fish increases in a fish tank the oxygen supply will still be the same but as the number of fish is more there will be less oxygen for each fish. 

High Water Temperature

The amount of dissolved oxygen in water is inversely proportional to the temperature of the water. It means that when the temperature of the water is high, the dissolved oxygen will be less in water whereas when the temperature is low, the dissolved oxygen levels are high.

ideal water temprature

It is really important to maintain a balanced water temperature to create a natural environment for your fish. The ideal living temperature for most fish is between 25 to 30 degrees celsius. 

Lack of Water Movement

Water movement is another important factor responsible for low oxygen levels in a fish tank. When the water is still and there is no flow the surface oxygen cannot reach the depth and fishes have to come up to the surface to breathe. 

Low Lighting and Plants

If your fish tank is at a place with low or no sunlight then the plants in your tank might be the reason for low oxygen levels. Plants are really important for fish tanks, they maintain the oxygen level of the water tank by taking carbon dioxide and releasing oxygen. But due to low sunlight plants cannot perform the process of photosynthesis and sometimes they consume oxygen and release carbon dioxide instead.  You should also check algae growth in your tank because algae also work just like plants.

Clogged Filters and Waste Accumulation

Cleaning and maintaining a fish tank is really important to prevent waste from getting accumulated. If your fish tank is not cleaned often the uneaten food and waste will get stuck in the filter and this can cause a dirty tank. Bacteria need dissolved oxygen to break down which contributes to reducing the dissolved oxygen in the fish tank. Also, the waste contains harmful gases like ammonia which can cause breathing problems in fishes.

Fish Medicines

Some fish medicines contain certain chemicals which can reduce the dissolved oxygen levels in the water.

These were some of the factors which affect the oxygen levels in the water. 

Simple Ways to Increase the Oxygen Level in a Fish Tank

Pour Water From a Height

Pouring water from a height will increase the flow of water and will dissolve more oxygen in the water. Just take an empty container and fill it with the existing aquarium water, then slowly pour the water from some height and repeat this process several times. This simple process can really be helpful for your fish in an emergency situation.

Change 50% Water of Tank

Another quick method to increase the dissolved oxygen level is to change the water by 50%. You can take out half the water from your tank and replace it with fresh water. Freshwater will have more oxygen and replacing it will increase the dissolved oxygen level. 

Stirring the Water Manually

Flowing water is very important to maintain oxygen levels in the tank. You can manually stir the water using a stick to keep the flow in water. Repeat this process several times when you feel the dissolved oxygen level in your fish tank is low. 

Using Ice Cubes

As we have told you above, maintaining an ideal water temperature is very important to keep a balanced dissolved oxygen level in the water. If you feel that the water temperature is high just put some ice cubes in a zip-closed bag and hold them at the top. This will lower the water temperature and will increase the amount of dissolved oxygen in the water. 

Battery-Powered Air Pump

battery powered air pump

You can use a battery-powered air pump if there is a frequent problem of power cuts in your area. A battery-powered air pump will ensure maintaining a proper oxygen level by a constant supply of oxygen. 

Hob Filters

Hob filter

Using a Hang on back ( HOB ) filter is one of the permanent and best methods to solve the problem of low oxygen in a fish tank. HOB filter is a small device that fits on top of the fish tank. Filtered water from HOB goes back to the aquarium and increases dissolved oxygen, also it aerates the water as the filtered water falls from a height. It is a good device as it distributes oxygen all over the tank.  

Spray Bar

spray bar

A spray bar comes with the canister filter mostly. It is attached to the canister filter and is placed at the bottom of the tank to evenly distribute oxygen throughout the tank. It releases bubbles that aerate the water. It is a good device to increase the oxygen levels in a tank.

Air Pump

air pump

An air pump can be used with an aquarium filter for best use. The air pump circulates the air inside the tank by pumping fresh air inside through air stone. 

These were some of the methods you can use to increase the amount of dissolved oxygen in a fish tank.

See Also: Can Fish Drown? | An Intriguing Quest! (How to Prevent?)

FAQs | Increase Oxygen In Fish Tank

Can Fish Die Because of Too Much Oxygen?

Yes, too much oxygen in a fish tank can cause problems like bubble disease to fishes.

What Are the Signs of Low Oxygen in a Fish Tank?

These are some of the changes you can notice in fish if there is a low oxygen level in the fish tank:

  • Coming to the water surface to breathe.
  • Less appetite.
  • Less movement. 
  • Fast gill movement.

How Long Can Fish Live With Low Oxygen?

A fish can live up to a maximum of 2 days with a low oxygen level.

How to Make Oxygen for Fish at Home Without Electricity?

You can use some of the simple methods listed above like changing 50% of tank water, stirring water manually and pouring water from a height.


In this blog post, we have listed some of the most effective methods of increasing oxygen levels in a fish tank. We hope that this gave answers to most users’ questions about “How to increase oxygen in a fish tank?”.

If you still have any questions regarding fish tank and fishes do leave it in the comment section down below.


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