Why are There Bubbles in My Fish Tank?


As a fishkeeper or an aquarium hobbyist, you may have noticed that your tank has bubbles in it. You may have even asked yourself why the bubbles are there, if they are harmful, and how to get rid of them? There are different reasons that this can occur. The goal of this post is to answer some of those questions for you.

Why are There Bubbles in My Fish Tank?

Bubbles in your fish tank are most commonly caused by agitation in your tank when you are filling it with water, and agitation is not necessarily harmful to your tank. Bubbles caused by agitation are usually located on the glass of the aquarium, and this can be an annoyance as they block the view of your aquarium. Fortunately, bubbles caused by agitation is harmless and it should dissipate with time. It is similar to the bubbles created when you shake a bottle of water.

Another common reason for bubbles in your fish tank is due to increasing water temperature. When water temperature rise, oxygen is released and the bubbles form. Keep in mind that cold water is capable of holding more oxygen than hot water. These bubbles that are formed may stick to the aquarium glass wall.

There are various other reasons why there may be bubbles in your fish tank. Bubbles can be caused by aquarium plants giving off beneficial oxygen to your setup, or the bubbles can be created by the fish. In fact, fish that are bubble nesters will intentionally create bubbles. The bubbles may be created unintentionally by the fish as well, especially if the fish are trying to breathe air from the surface of the water.

Bubbles can be located in various areas of the fish tank. It can appear on the surface of the water, the sides of the tank, on the aquarium plants, or even on the fish.

Keep in mind that not all bubbles are necessarily bad. Many of the bubbles are harmless. Nonetheless, if the cause of the bubbles are not clear, it may be worth investigating the cause of it.

Bubbles on Surface of Fish Tank

Why is There Foam in My Fish Tank?

Foam in your fish tank is most likely caused by a combination of proteins in the water and agitation. Water agitation naturally creates bubbles, but the proteins prevents the bubbles from popping by coating it. This makes the bubbles to accumulate and remain on the water surface for an extended period of time.

While foam is not necessarily harmful, if there is a lot of foam accumulating on the surface of the water, it may be a sign of unclean water. As mentioned, foam is often produced as a result of protein build up. Therefore, aquariums with lots of foam may have a foul odor.

If unclean water is the cause of foam, the solution is obvious. Simply keep the tank clean by doing more regular water changes and maintaining the aquarium filter.

If there’s a lot of foam even though the tank water is clean, reducing the level of water agitation may help. By adjusting the outflow on the aquarium filter, the amount of foam produced may be reduced. Simply changing the angle of the outflow may affect the amount of foam created as well.

Bubbles on Aquarium Plants

Bubbles can appear in your tank due to the aquarium plants. As the plants grow and absorb light, they give off oxygen due to photosynthesis. The oxygen will sit on the leaves as little jewel-like bubbles. This is known as pearling, and it can be a sign of a healthy aquarium plant. If you have fast growing plants, you will see the pearling more often than on a slow growing plant. If you are not seeing the pearling of oxygen on your aquarium plant, it may be because the oxygen is being absorbed into the water right away.

Bubbles on the Surface of the Water

One of the major cause of bubbles appearing on the surface of the water is the aquarium filter. These bubbles often float on the surface of the water, until it attaches itself to another floating object or edge of the tank.

Aquarium filters maintain water quality by pushing water through various filtration media. This includes mechanical, biological, and chemical filtration media. Naturally, this process creates water flow in the aquarium, along with some bubbles. Therefore, it’s very normal to see bubbles in the edges or corners of the aquarium.

However, if there is a lot of bubbles forming, the aquarium filter may need to be examined. It may be set up in a way that creates bubbles unnecessarily. The first thing to check is the flow rate. If the filter is flowing too strong, consider reducing the flow rate. Many aquarium filters have the ability to adjust the flow rate. The next thing to check is the angle of the filter outflow. If the outflow is angled perpendicular to the surface of the water, it is going to create lots of bubbles. In contrast, if the outflow is angled parallel to the surface of the water, less bubbles will be created. Some filter outflows can be adjusted to the desired angle. However, even if the filter outflow is not adjustable, this can often be manipulated by adjusting the water level. If the water level is significantly lower than the filter outflow, the water will drop down into the surface of the water at a perpendicular angle. This will cause a lot of bubbles to form, similar to a waterfall. The goal is to allow the water to gently flow across the surface of the water, similar to a river.

Bubbles in Your Betta Fish Tank

There’s a good chance that there are bubbles in a Betta fish tank. One of the reasons for the bubbles forming is because Betta fish are bubble nesters. The male Betta fish would create a bubble nest on the surface of the water in preparation of a spawn. This means that a male Betta fish may regularly make a bubble nest, even if there are no female Betta fish nearby. These empty bubble nests can be removed, but it is not necessary a bad thing. In fact, a male Betta fish that is actively creating bubble nests is good, since it is a reflection of its good health.

Another reason why there may be bubbles in a Betta fish tank is because Betta fish often breathe air from the surface of the water. As labyrinth fish, they are able to absorb oxygen from the surface, in addition to their gills. As they come to the surface and gulp in some air, small bubbles may be created.

Why are My Fish Blowing Bubbles?

If the fish are gulping for air at the surface of the water, this may cause bubbles to form. However, this may be a sign of an unhealthy environment as well.

With the exception of labyrinth fish, such as Betta fish, most fish do not have the ability to take in oxygen from the surface of the water. Most fish rely solely on their gills to absorb oxygen from the water. If these fish are trying to gulp in air from the surface, this may be a indication of a lack of oxygen. The water may contain harmful chemicals such as chlorine and ammonia, causing the fish to behave in such manner as well.

If the fish are gulping for air from the surface of the water, this may create lots of bubbles. This may be a sign of distress, and immediate attention may be required. Identifying the cause of the behavior, and correcting any issues is crucial. Testing the water parameters in the aquarium is one of the ways to identify issues.

How to Get Rid of Bubbles in Your Aquarium

While bubbles aren’t necessarily bad, excessive bubbles forming in an aquarium could be an indication of poor water quality. This is especially true of the bubbles are turning into foam. Foam is created when there is protein in the water. The protein covers the bubbles, which prevents it from popping. This leads to the formation of foam.

Assuming the bubbles in the fish tank is caused by poor water quality, the best way to get rid of bubbles is to improve the water quality. This can be done by cleaning your aquarium regularly. Changing 10-20% of the aquarium water may be a good start. By regularly vacuuming the substrate and removing the excess waste, water parameters in the aquarium may improve significantly. While many people who see a dirty aquarium will be tempted to do a large water change, this is not always the best option. It is usually better to increase the frequency of the water changes, not the amount of water changed during each session. Large and drastic water changes can be harmful to the fish. Cleaning the filtration system may be beneficial as well, especially if it is clogged up.

Another way to get rid of bubbles is to adjust the outflow of the aquarium filter. By reducing the strength and angle of the outflow, the amount of bubbles that are formed can be reduced or eliminated.

Lastly, if the bubbles were caused by rising water temperature, it will disappear by itself. You simply need to wait for the water temperature to stabilize.

Why Does My Fish Have Bubbles On It?

If you notice bubbles on your fish, this could be a sign of trouble.

Bubbles on the fish could be caused by Gas Bubble Disease. This disease is common in fish that are exposed to water that is super saturated with natural gasses like oxygen, carbon dioxide, and nitrogen. This is a disease that mainly affects fish that live in aquariums. It makes itself known whenever there is a change in temperature in the aquarium. These bubbles can form on the eyes, skin, gills, or fins of the fish. These trapped bubbles can result in the death of your fish.

If the bubbles on the fish is very small and it resembles salt grain, this may be a sign of a disease called Ich. This is a parasitic disease that is also known as white spot disease. This disease is deadly, but treatment and recovery is possible if it is detected early.

All Bubbles Aren’t Bad

Bubbles will naturally form in an aquatic environment, so they aren’t necessarily all bad. Even in a healthy natural lake or river, there may be bubbles that form in certain areas.

In an aquarium, it is completely normal to see bubbles forming in near the filtration system or edge of the tank. Keep in mind that some aquarium has air stones installed that creates bubbles on purpose as well.

If the bubbles are disappearing and the bubbles aren’t on the fish, there is no immediate need to be alarmed. Most bubbles are harmless, and they aren’t a sign of trouble.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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