How to Add Oxygen to a Gold Fish Tank?

Oxygen is an uber-important element that is necessary for all living things, including fish. Many elements in your fish tank can contribute to low oxygen levels and cause difficulties for your goldfish.

Low oxygen levels in your aquarium can be pretty alarming for your fish as they can cause a bunch of health problems.

So, let’s discuss how you can increase the oxygen level in your goldfish aquarium.

Ways to Increase Oxygen In Your Aquarium

Below are some ways you can use to increase oxygen in your fish aquarium:

Increase Surface Agitation

Surface agitation is possibly the greatest way to increase oxygen levels in your goldfish aquarium.

You can increase surface agitation in a number of ways.

Aquarium Bubblers

These bubblers are attached to an air pump by an airline. They are available in various shapes and sizes.

They can be placed below gravel or even connected to other ornaments in a fish tank, such as treasure chests.

The treasure chest can be pushed open due to the pressure of the rapidly releasing streams of bubbles and oxygen.

Also read: Why Does My Fish Tank Have Bubbles on the Glass?

HOB Filters

HOB filters are hung behind an aquarium. They release filtered water back on the surface of the fish tank.

This release of water creates movement in the surface, increasing the surface area that allows oxygen exchange to take place.


Powerheads can also be installed in your goldfish aquarium to create an increased water flow.


Wavemakers are machines that create waves that resemble naturally occurring waves.

This is done through the creation of a water surge that agitates the surface of the aquarium water.

Spray Bars

Spray bars sprinkle water slowly back into the fish tank via your filter outlet. They serve a purpose similar to the water outlet of HOB filters.

However, sprays bars are only meant to be used with external filters.

Water Pump

Last but not least, a great solution for water agitation is water pumping.

Water pumps create water movements that aid in the process of oxygen exchange.

Reduce Overcrowding

In order to maintain adequate oxygen levels, you will have to reduce the goldfish within a tank.

You can give them to a friend or relative or you can upgrade to a much larger aquarium. You also have the option to separate your fish and put them in different tanks.

However, this may require more maintenance.

Balance Water Temperatures

You will have to balance the water temperature as even a few degrees can make a massive difference.

You can try changing the water by adding a certain percentage of cooler water to the existing aquarium water.

You can also fill a bag with ice cubes and place it in the fish tank to let the water cool down.

The lights and heaters can have a major impact on the temperature of the aquarium. Use a thermometer to measure the water temperature.

If you feel like its high, try turning off the lights and the heater.

Keep the Tank Clean

Ammonia spikes are a serious issue that can lead your fish pets to their deathbed. The only way you can prevent this from occurring is by conducting frequent water changes.

Draining out all the waste from the aquarium will definitely increase the capacity of water to carry oxygen.

Also, make sure that you get rid of any algae from the water.

Install a Good Water Filter

To enhance the movement of water, you will require a really good water filter— one that has a high flow-rate and has a great output pump.

It will cause the aquarium water to move around which will help with oxygen exchange throughout the aquarium.

Cleaning the water filter that is not functioning at full capacity can also help in the movement of water.

Reduce the Number of Plants

Too many plants can cause oxygen levels to deplete rapidly when placed in the dark.

To maintain balanced oxygen levels, it is recommended that you stock only a limited number of plants in an aquarium.

You can also expose your aquarium to a few extra minutes of sunlight so that the plants can produce more oxygen.

Also read: 20 Best Plants for Goldfish Tank

Check Labels Before Adding Chemicals

Before adding any chemicals to the aquarium water, always read the label and instructions.

This is to ensure that it doesn’t contain any elements that will negatively impact the oxygen levels of the water.

Testing Oxygen Levels in a Goldfish Aquarium

How can you tell if the oxygen level in the aquarium is low? You can measure the amount of oxygen within the water using an oxygen testing kit.

However, testing kits are not all that accurate, most of the times. So here are some signs that indicate that the oxygen levels in your tank are low.

Signs of Low Oxygen in a Goldfish Aquarium

Here are some signs that the oxygen levels are low in the goldfish tank:

Movements Of Your Goldfish

Keep an eye on the movement of your beloved goldfish pets as that is an indication of a low oxygen level.

The shortage of oxygen within your aquarium will cause your goldfish to become sluggish and reduce their movements.

Your goldfish will swim at a very slow pace and will also avoid eating.

Movement of the Gills

When oxygen levels drop down to unreasonably low levels, you will see that the gills of your goldfish will start moving excessively and a lot faster.

This is an attempt to soak in all the remaining oxygen in order to survive.

Oftentimes, it becomes very obvious that your fish is having trouble breathing.


If the oxygen within the tank drops at a critically low level, your goldfish will start coming up to the surface of the water.

They do so in an attempt to get oxygen from the air above the tank.

In the event that all or the majority of your goldfish are surfacing and appear to be gasping for air, you’ll know that oxygen has either hit an all-time low or has vanished completely.

This will require you to take immediate action as your fish could die.

Causes of Low Oxygen Levels

There are multiple factors that can cause the oxygen levels of your goldfish tank to drop.

Each one of these problems, however, has simple and effective solutions, which we have covered in the section above.

Here are some factors that can cause oxygen levels of your fish tank to drop.


Goldfish, like all other living things, require an ample amount of oxygen to breathe. However, a certain-sized fish tank can only house a number of fish.

A small aquarium can have many implications for its inhabitants. Stuffing too many fish in a small aquarium will cause overcrowding, which will result in a shortage of oxygen.

Basically, overcrowding implies that there are too many fish in an aquarium and there is not enough oxygen in the water to sustain them.

Also read: What Fish Can Live With Goldfish? 10 Best Goldfish Tank mates

Increased Water Temperature

Another factor that can cause the oxygen levels to drop is the high water temperature of the aquarium water. Hot water holds much less oxygen as compared to cold water.

It may be difficult to manage the water temperature as certain fish and plants might need warm water to survive.

Too Much Waste

The more fish you have in an aquarium, the more waste you’ll have to clean.

The presence of excessive waste in the water can cause ammonia spikes. Nitrite and ammonia reduce dissolved oxygen in the tank.

Also, too many algae can also deplete the capacity of water to carry oxygen.

Not Enough Water Movement

Stagnant water or not enough water movement can cause a decrease in the oxygen levels within a fish tank.

This especially applies to the lower portion of the tank, as the least amount of oxygen exchange takes place there.

Too Many Live Plants

Plants are one of the most important elements that are present in an aquarium.

This may seem a little eccentric but plants tend to absorb more carbon dioxide from the water and produce more oxygen in the presence of light.

When the lights are off, the opposite usually happens. Plants start absorbing the oxygen, making it hard for your fish to breathe.


Some chemicals that are used to treat aquarium water can also impact the oxygen-carrying capacity of water. So always be careful.


Low oxygen in your aquarium can be very alarming for your beautiful goldfish pets.

It’s extremely important for you to pinpoint the reason behind low oxygen levels and remedy that as soon as you can.

Your fish definitely won’t be able to survive if they can breathe for too long.

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