How to add oxygen to fish tank guide to oxygenating your home tankAdd oxygen to fish tank to improve oxygen levels and reduce the chances of fish suffocation. You can oxygenate your tank manually by scooping some aquarium water into a jar and gently pouring it back. It causes surface agitation, and water movement and allows air to be incorporated into the water.

Read on to learn about different techniques by which you can add oxygen to your fish tank.

How To Add Oxygen To Fish Tank

Here are some effective techniques to help add oxygen to your fish tank. Oxygen diffuses into the water through the air, so the more you can incorporate it, the higher the oxygen levels in your fish tank. Hence, the methods below tackle the issue of oxygen deficiency; however, they provide immediate but temporary solutions

1. Pouring Water From a Height

Pouring some water into the tank from a height will increase Its Oxygen Levels. For an immediate solution to low oxygen levels in an aquarium, manually pour some aquarium water into the tank from a height. It is the simplest method to oxygenate a tank. Here are some steps to follow:

  • Fill a clean jar with water from your aquarium
  • Lift the jar of water and hold it at a height directly above the aquarium
  • Then gently pour back the water into the tank
  • This method imitates rainfall while aerating the water and gradually infusing oxygen into the tank
  • Repeat this process many times

– Tip

This method may cause the tank substrate to stir. You can avoid this by putting a clean bowl at the bottom of the tank. Get one that would not float away, then pour the water from the jar over this area. It is the best way to add oxygen to a tank without a pump.

2. Perform Large Water Changes

You can increase the oxygen content by performing a water change of up to 50 percent of the tank volume. The freshwater introduced would have more oxygen content, thereby increasing the level in the aquarium.

3. Use an Air Pump

Another method to oxygenate fish tank is by using an air pump. The air pump generates air which disturbs the water surface and improves water circulation.

However, we recommend a battery-powered air pump (get an AC variant that can automatically switch to an internal rechargeable). These types are efficient and reliable. They continue producing air, causing water flow even after power cuts. So, the oxygen level remains at optimal levels at all times.

4. Use Ice Cubes

This last suggestion does not incorporate air into the aquarium, but it helps increase oxygen levels. You can add oxygen to fishbowl by reducing its water temperature. This fast method involves using ice cubes to lower tank temperature. First, put some ice cubes in a Ziplock bag, then insert the bag into the water and hold on to it.

How To Have Permanent Solutions for Tackling Oxygen Deficiency

Try out the following suggestions for a more long-lasting remedy to low oxygen levels in fish tanks

1. Use a Hang-on-Back Filter

These filters are portable and easy to use. They are a great way to have good oxygen levels in a tank constantly. The HOB filter is usually hung on the tank. Then, it takes in water from the bottom of the tank and releases it at the top.

Hence, the filtered water that flows through the HOB filter falls from a height that aerates the water. Also, the oxygenated water is evenly distributed through the tank. Alternatively, add an air stone to your tank filter to aerate the water.

2. Use a Spray Bar

Most aquarium canister filter comes with a spray bar. It is a perfect device for aerating a tank, so use it. The spray bar helps filtered water circulate through the tank surface, exposing the water to air and increasing the oxygen levels.

3. Use a Wavemaker

You can increase oxygen in fish tank without a pump by using a wavemaker. Wavemakers increase water circulation by breaking its surface tension. The wave moves throughout the tank surface allowing air to contact the aquarium water, thereby causing gas exchange.

Furthermore, the wavemaker allows you to set the appropriate speed of water flow throughout the day. Hence, the water current produced would not bother your fish.

4. Controlling Elevated Temperature Levels

A temperature rise reduces oxygen levels in a tank. They make it hard for the fish to breathe and encourage harmful bacteria growth, which further depletes the oxygen levels in the tank. Apart from reducing the temperature with ice cubes, you can opt for a more permanent solution like installing a chiller unit. The chiller unit uses refrigerant to reduce the tank’s temperature.

The cooler the temperature, the less oxygen the fish consumes. They are particularly amazing for warm climates because they keep the tank from running hot. However, remember that each species has a different requirement. Not all fish require a cold environment, so research and keep your fish comfortable in the ideal habitat.

Adding Oxygen Without Electricity

Here are three ways to add oxygen to your tank without electricity

  • Solar power fountain pumps
  • Aquarium plants
  • Oxygen tablet

1. Use Solar Fountain Pumps.

Using a solar-powered fountain is another way to add oxygen to water in a fish tank. It helps increase surface agitation and water movement in the aquarium.

2. Aquarium Plants

Aquarium plants are a natural method to add oxygen to a fish tank. They extract the carbon dioxide produced by the fish and release oxygen into the water. This exchange is safe, and it creates a natural habitat for the fish to live in while keeping up the oxygen levels.

You can plant hardy and quick-growing plants. Some plant suggestions include; carpet plants like water wisteria, dwarf hair grass, java fern, fanwort, green tiger lotus, water sprite, Amazon sword, hornwort, eelgrass, and java moss. They are beginner-friendly and would form a thick canopy in no time. Also, they are stunning and easy to care for.

3. Add Oxygen Tablet

Using oxygen tablets to increase oxygenation in an aquarium is not popular. The tablets are made up primarily of hydrogen peroxide and other sodium compounds. It reacts with water and releases oxygen atoms in the form of bubbles as it dissolves. Please note that oxygen tablets are temporary sources of oxygen and should not be considered a sole source.

They are commonly used to generate oxygen for fish during transit. However, it can also be used as an oxygen boost in tanks due to its rapid release. Furthermore, they have no shelf life as long as you keep them away from moisture and at room temperature.

Adding Oxygen Without a Pump

  • Put live plants in your tank
  • Install a powerful filter that has a modifiable flow rate
  • Improve water surface area and surface agitation using manual methods like manually pouring water into the tank

How To Know if the Oxygen in The Tank Is Low?

There are effective ways to tell if your tank has low dissolved oxygen levels.

  1. Use a dissolved oxygen meter
  2. Observe your Fish’s Behavior

1. Dissolved Oxygen Meter

This method is a bit straightforward. Get a reliable oxygen meter and monitor the oxygen levels in the tank from time to time.

2. Fish Behaviour

Fish behavior involves looking out for signs to help you detect when a tank has low oxygen levels. Here are some of the signs:

– Fish Gasping at the Water Surface

If you see the fish at the top of the water with its mouth wide open, then it is likely the oxygen levels are low. Please note that some fish like the beta and labyrinth species swims to the water surface from time to time. But if all the fish in the tank seem to come up frequently, there might be a problem.

In some cases, the fish would exhibit signs of labored breathing. You would notice rapid gill movement as your fish tries to suck up oxygen to survive.

– Fish Is Sluggish and Lacks Appetite

If your fish is eating less and not moving around the aquarium as often, then the tank may have low oxygen levels.

How To Know The Causes of Low Oxygen Levels?

Here are nine reasons why the oxygen levels in your tank are inadequate.

1. Overstocking

If you put too many fish in a small tank, there would be low oxygen levels. This is because the fish use up the oxygen faster than how it gets replaced. Hence, overstocking is a top reason why a tank would have fewer oxygen levels. To remedy this problem, get a bigger tank or separate the fish and put fewer fish in a tank.

2. Elevated Water Temperature

As mentioned earlier, high water temperature causes a decrease in oxygen levels in a tank. Simply put, high-temperature water can not hold as much oxygen as cooler water. Remember to reduce the temperature by using ice cubes or a chiller.

3. No Water Movement

Movement encourages water aeration. So, if your tank water is stagnant, the oxygen level would be low.

4. Low Lighting

If your main source of oxygen is live plants, then low lighting can lead to the low oxygen content in your tank. Plants require adequate lighting to extract carbon dioxide and give off oxygen, or the process becomes reversed. This means that in low lighting, the plant would use up the oxygen in the tank instead. The remedy is to provide ideal lighting or take out some live plants.

5. Chemicals and Medications

If you are using chemicals and medication in your tank, the oxygen levels may drop. The remedy is to read the instructions on the medication or chemical to know if it has an adverse effect on the tank’s oxygen levels.

6. Absence of Air Bubbles

Air bubbles are quite beneficial as they help oxygenate the fish tank. The bubbles introduce carbon dioxide into the tank, which is beneficial to the live plants. Also, it increases water movement in an aquarium, thereby inhibiting algae growth.

7. Algae Growth

The algae in a tank reduce the water’s capacity to hold oxygen. The remedy is to increase water movement and clean the tank frequently.

8. Issues Associated With Fishbowls

Most beginner fish keepers make a mistake by buying small fishbowls. The bowls have rounded sides and small openings, making it difficult for oxygenation to happen, unlike in a regular tank. Also, they do not have enough surface area.

The solution is to add oxygen drops or an air stone, but this would only work for some time. Alternatively, keep a few fish in the bowl or transfer the fish into a bigger rectangular tank.

9. Too Much Waste product

In an overstocked tank, waste production would be rapid, producing more ammonia and nitrites. These harmful toxins deplete the oxygen levels in an aquarium because the water cannot hold dissolved oxygen. The remedy is to clean the tank to get rid of the waste, which would increase the water’s oxygen holding capacity. Furthermore, clean the filter to improve its efficiency of removing waste.

How To Detect Signs To That The Tank has Too Much Oxygen?

Here are some signs that indicate too much oxygen in a fish tank.

● Cloudy Eyes

Co2 penetrates cells in the fish’s eyes to help improve vision. So, the fish would have cloudy eyes and struggle to see in its absence.

● Bloated Fish

Some air bubbles get trapped under the fish scales, causing the fish to swell.

● Death

Hyper-oxygenation can cause a series of unexplained death in your aquarium.

How To Reduce the Oxygen Content

If you are trying to tackle the issue of hyper-oxygenation, you should try these easy remedies

  • Add more plants to your tank so they can consume the excess oxygen
  • Install a bubbler near your tank surface, so it pulls out the excess oxygen beneath your fish scales
  • Install fluorescent bulbs instead of LEDs as they emit heat and produce less wavelength
  • Perform frequent water changes
  • Install a powerful water filter to improve circulation resulting in fewer fish bloating
  • Monitor your oxygen levels


1. Are Oxygen Tablets a Safe Method To Add Oxygen To Fish Tank?

No, an oxygen tablet is not safe. The main compound of the oxygen tablet is hydrogen peroxide which is a bleaching agent. This can cause the fish to develop skin and gill problems or bleach any fish eggs present in the aquarium. Hence, we do not recommend the oxygen tablet for long-term use.

2. How Much Oxygen Does a Fish Need in an Aquarium?

There is no one-size-fits-all in this case as the requirement for each fish differs. For instance, some freshwater fish require 8.3 parts per million PPM, while some saltwater fish can tolerate 6.4-7.0 parts per million. However, at least five parts per million PPM of dissolved oxygen and above is a fair amount to oxygenate water for fish. 

But, if the dissolved oxygen level is less than 2 PPM or less, the fish can suffocate. Also, note that a fish may struggle to live without dissolved oxygen only for about two days, depending on its health status.

3. Is Too Much Oxygen Harmful To Fish?

Yes, high oxygen levels can harm a fish. As we now know that too little oxygen kills, too much oxygen can also be detrimental to the fish’s health. When the oxygen content is too high, the fish is exposed to lethal gas bubble disease.

Visible bubbles would begin to form in the tissues of the fish. You would notice them on its eyes, gills, and fins. They may even form in the fish’s heart which can be fatal.

4. What Is the Relationship Between Aeration and Oxygenation?

Oxygenation refers to the amount of oxygen that gets dissolved in water, while aeration refers to the water flow or movement that can lead to oxygenation

5. How Do I Know if the Oxygen Level in My Fish Tank is Too High

How to add oxygen to fish tankYou can tell the oxygen level is too high if you notice air bubbles escaping at the water surface. Also, you can use a portable dissolved oxygen meter. Furthermore, like in the case of oxygen insufficiency, hyper-oxygenation would cause the fish to behave abnormally.


Oxygen is essential to fish survival. So, here are some tips to help you add oxygen to your fish tank:

  • Use an air pump to aerate the water and the oxygen level
  • Install a chiller to reduce the water temperature
  • Use a solar power fountain in your tank as it increases the water movement
  • Planting different live plants in your tank would also increase the oxygen

However, excessive oxygen content in a tank can cause lethal gas bubbles disease in the fish tissue when in excess quantity, which can be fatal. Hence, make sure to monitor the oxygen levels in your aquarium or lookout for signs of insufficiency.

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