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How to Increase Oxygen in Fish Tank? (8 Simple Ways)

If you are wondering how to increase oxygen in your fish tank then you are at the right place.

In this article, I am going to show you some ways to increase oxygen in your fish tank in case of an emergency.

I will also share with you some other ways that will help you to solve the low oxygen problem in your fish tank completely.

In case of emergency, you can instantly increase the oxygen level in your aquarium by simply pouring down some aquarium water using a jar from some height.

You can also do a large water change of up to 50% of water to increase oxygen in the fish tank.

Coming to the permanent solution for low oxygen levels includes using an air pump.

The other ways include using a HOB filter or a spray bar.

How to Increase Oxygen in the Fish Tank image

But before that let’s make it clear if your fish tank actually has low oxygen.

How to know if your tank has a low oxygen level?

There are several signs that can help you to know if you are tank has a low oxygen level or not.

Fishes gasping on the surface

The most obvious sign is when the fishes come to the surface of the water and gasping with a wide-open mouth.

Some fish like Betta usually come on the surface to get some oxygen but if you are seeing all the fish coming on the surface or at least some fish coming on the surface more frequently that requires a lot of oxygen then it is a solid sign that your fish tank has low oxygen level.

Fishes moving around less

If you noticed your fishes are moving around less i.e. they are swimming less or swimming slowly than usual then it may be because your aquarium has a low oxygen level.

Fishes eating less

If you noticed all the fishes in your aquarium are eating less food then in this could be a sign that your aquarium has a low oxygen level.

Labored breathing

If you noticed your fishes are breathing rapidly and noticed a more rapid gill movement then this is a strong sign that your aquarium has a low oxygen level.

Now let’s see the causes of low oxygen in your aquarium.

How much oxygen does a fish require?

It really varies from fish to fish but according to FWS 5 parts per million PPM of dissolved Oxygen or higher is a good rule of thumb.

Most of the fishes will start suffocating if the dissolved oxygen level is decreased to 2 PPM or lower.

Ok. So now that we know the sufficient amount of oxygen level in the aquarium tank, you may be wondering if too much oxygen kills a fish in a tank.

Believe it or not but the answer is YES!

As the low level of Oxygen, a high level of Oxygen is also bad for fish.

A very high level of oxygen in the tank causes a lethal gas bubble disease.

In the fish tank having high Oxygen levels, bubbles started formin on the body tissues of the fish.

You can see these bubbles on their gills, eyes, and fins.

If these bubbles start forming in the fish’s heart then it can lead to death.

Now let’s see how you can increase oxygen in your saltwater or freshwater aquarium.

Ways to increase oxygen in your tank in an emergency

Ok so now you know that your aquarium doesn’t have sufficient oxygen for fish.

Your fish is suffocating due to lack of oxygen and they require instant oxygen.

Here I am going to share with you some ways to increase oxygen in your tank instantly.

Pouring water from some height

The simplest way to increase oxygen in your tank instantly is by slowly pouring water into the aquarium from some height.

The steps go like this:

Step 1: Take a clean jar and fill it with water from your aquarium

Step 2: Hold the jar above the aquarium and pour down water from the height.

When you pour down the water from the height it will help to aerate the water and ultimately increase the oxygen level in the aquarium.

Large water change

Another way to increase the oxygen level in the aquarium is to do a large water change (up to 50% of the tank)

The freshwater that you introduced in the tank will have more oxygen that will help to increase the oxygen level in the tank.

Use ice cubes

If the oxygen level in your tank is decreased due to the high water temperature of the tank water then you can cool down the water by putting some ice cubes into a zip-closed bag and then holding that bags into the aquarium.

Use a battery-powered air pump

If the oxygen level in your aquarium is decreased during power cuts then it is wise to get a battery-powered air pump that you can use during a power out-cut to keep the water moving.

Ways to increase oxygen in the fish tank (Permanent solutions)

The ways mentioned above are great in case of emergency but now we are going to look at some permanent solution to cope with the low-level oxygen in your tank.

Use a HOB filter

HOB filters are great to increase the Oxygen level in your aquarium.

They are very small and very easy to use.

The filtered water from the HOB filter will fall down from a height that will help to aerate the water.

Also, the water will go deep into the tank that will distribute the oxygen at the bottom and throughout the tank.

List of the Best HOB Filters for Freshwater Aquariums

List of the Best HOB Filters for Saltwater Aquariums

Use a spray bar

If you are using a canister filter for filtering your aquarium then it may have come with a spray bar. If you are not using it then this is the perfect time to take advantage of it.

If you don’t have a spray bar then I have found a very good sprayer at Amazon.com here and Amazon.co.uk here.

A spray bar basically helps to distribute the filtered water throughout the surface of the tank that will provide more exposure to the water to aerate, which will ultimately increase the oxygen level in your tank.

List of the Best Canister Filters

Use fountain

If you have a low oxygen level in your pond then using a fountain is a great way to increase the oxygen level in the pond.

Use air pump

Using an air pump is a straight forward way to increase oxygen in your aquarium.

It is meant for it!

An air pump will take air and release it into the aquarium tank through an air stone.

There are a lot of air pumps available for the aquarium but the problem with most of them is that they are not reliable and are a bit noisy.

However, there is an air pump that comes from a reputed brand and doesn’t make noise.

You can check its customer reviews and price at Amazon.com here and Amazon.co.uk here.

ways to increase oxygen in your fish tank infographic

What causes a lack of oxygen in fish tanks?

Overstocking

Overstocking is usually the reason for low oxygen in fish tanks.

It is pretty obvious that if you put a lot of fish in a relatively small aquarium then there will be a shortage of oxygen in the tank that causes low oxygen level in the aquarium.

Elevated water temperature

If the water temperature of your aquarium is high then this could be a reason for a low oxygen level in your aquarium.

Basically, high-temperature water cannot hold as much oxygen as cold water so the rising temperature of your aquarium tank could be a reason for the low oxygen level in your aquarium

Lack of water movement

Lack of water movement also causes low oxygen levels because it is the movement of water that helps to aerate the water in the aquarium.

Low lighting

If your aquarium has live plants then this could be a reason for the low oxygen levels in your aquarium.

Usually, we see advice that plants actually help to oxygenate the aquarium and it is true but if there is not sufficient lighting in the aquarium with live plants then instead of taking Carbon dioxide and releasing Oxygen the plant starts to take Oxygen and release Carbon dioxide that reduces the Oxygen level in the water.

Also if you have Algae in your aquarium then it works the same way as live plants so it also requires a healthy amount of lighting.

Chemicals and medications

If you are using certain chemicals and medications then it may be causing low oxygen levels in your aquarium.

So now that we know the causes of low oxygen in your aquarium.

It makes sense to know how much oxygen does a fish actually require.

Causes of low oxygen in a fish tank infographic

Conclusion

So as you can see there are different ways to increase oxygen in the fish tank.

If you are in an emergency then simply pouring the aquarium water with a jar from some height can help to increase oxygen in the tank or performing a large water change can help to increase oxygen in the tank.

If oxygen levels are decreased in the fish tank due to high water temperature then keeping some ice cubes in a zip-closed bag inside the aquarium will cool down the water and help to increase oxygen in the aquarium.

If you are facing the problem of low oxygen level during power out-cuts then using a battery-powered air pump will oxygenated water during power out-cuts.

The permanent solution for the decreased oxygen level in the fish tank includes using a HOB filter or a spray bar or air pump.

If you want to increase oxygen in your pond then using a fountain is a great way to oxygenate the pond water.

FAQ

How do you oxygenate a fish tank?

There are several ways to oxygenate a fish tank. The simplest way is to use an air pump if you are not using it.
In case of an emergency, you can do the following things to increase oxygen in the fish tank:
1. Pour down the aquarium water from some height into the aquarium
2. Do a large water change (up to 50%) of the tank
3. Use ice cubes

For the permanent solution for low oxygen issue, you can do the following things:
1. Use HOB filter
2. Use a spray bar
3. Use an air pump

If you are facing low oxygen issues during power cuts then you can use a battery-powered air pump to cope with the problem.
In case you want to increase oxygen in your pond using a fountain is a great way to oxygenate pond.

Can you have too much oxygen in a fish tank?

Yes, you can have too much oxygen in a fish tank and it is harmful to your fish. It causes lethal gas bubble disease.

Do filters add oxygen in fish tanks?

Filters like HOB filters can add oxygen in the fish tank. The filtered water coming out from the HOB filter gets exposed to air before falling into the tank which helps to oxygenate the water.

How can I oxygenate my fish tank without electricity?

There are a couple of ways to oxygenate a fish tank without electricity.
The first way is simply pouring down the water of your aquarium using a jar or pitcher from some height it into the aquarium. This way the water will get exposed to the air which will oxygenate it.
The another way to oxygenate the fish tank is by performing a large water change (up to 50%) of the tank water.
The newly introduced water will have more Oxygen, this way you can cope with the low oxygen level problem in your tank.

Can you turn off a fish tank pump at night?

If you have an air pump which is separate from the main filtration system of your aquarium then it should not cause any problem if you turn it off during the night.

Why are my fish at the top of the tank gasping for air?

When your fish comes on the top gasping for air it is a strong sign that the aquarium does not have a sufficient amount of oxygen.
As the surface of the water has the highest dissolved oxygen fish come to the surface to take oxygen.

How long can a fish live without oxygen?

A fish can live up to 2 days without oxygen.

Are bubbles good for a fish tank?

Air bubbles help to oxygenate the fish tank. The air bubbles also introduce carbon dioxide in the fish tank that is good for the plants in the aquarium.
The plants take carbon dioxide and produce oxygen for the fish.
Air bubbles also keep the water moving in the fish tank so it reduces the growth of the algae.

Why do fish go to the top of the tank?

When there is a lack of oxygen in the tank fish usually go on the surface to take oxygen because the surface has the highest amount of dissolved oxygen.

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