Why are There Bubbles in My Fish Tank?


As a keeper of fish or just 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 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, they can be an annoyance as they block the view of all your hard work setting up your aquarium. Think of shaking up a bottle with water in it. The bubbles that then form as a result are harmless and they should dissipate with time.

Bubbles can be caused by aquarium plants giving off beneficial oxygen to your setup, or the bubbles can form from the fish themselves that live in the aquarium, if they are bubble nesters. The fish could also be causing bubbles to appear if they are in need of a water change, making the bubbles as they breathe air on the surface of the water.

 Bubbles can be on the surface of the water, the sides of the tank, plants, or even on the fish. Bubbles can even be used as decor. The important information to know is, that when you notice unexplained bubbles in your tank, that not all bubbles are bad. Take a moment to decide where the bubbles are coming from, and you should easily be able to track down the reason they are appearing.

Bubbles on Surface of Fish Tank

Why is there foam in my fish tank?

Foam in your aquarium set up is most likely the result of water agitation, and proteins in the water. If there are proteins in the water it could make the bubbles hang around for quite some time. Proteins can coat the bubbles, and that will cause them to have a foul odor, and to not pop. The foamy bubbles left behind with protein build up is an indicator that your aquarium needs to be cleaned. Dirty aquarium filters and debris in the tank can cause this as well. If they are left uncared for, they will remain in your aquarium for a long time. One method to help keep bubbles down to a minimum is to pour the water in slowly and try not to agitate the water. Another method is to instill a regular cleaning and caring routine for your aquarium.

Bubbles on aquarium plants

Bubbles can occur in your tank due to the aquarium plants that you have growing. As the plants grow and absorb light, they are giving off gases due to photosynthesis. Oxygen will sit on the leaves in little jewel-like bubbles. This is known as pearling, and it can be a sign of a healthy aquarium. If you have fast growing plants, you will see the pearling more easily than on a slow growing plant. If you are not seeing the pearling of oxygen, then that could mean that the water in your tank is absorbing it, and that means that your tank needs more oxygen. Different aquarium plants have different needs, and it is important to know what your aquarium plants will need to thrive before placing them in your tank.

Bubbles on the surface of the water

Bubbles in your aquarium can be caused by your filter. These bubbles can be seen floating on the surface of the water. At first glance, you will notice the bubbles free floating, they do this until they come in contact with a surface to attach to. Usually this is the sides of the tank, or perhaps a plant sticking up out of the water. Unless you have a broken filter, you will note that the filter itself is not the one responsible for the bubbles you’ve spotted in your aquarium, but rather the filter outlet is to blame. The filter outlet is the part of the filter that returns clean water to your tank. You will want to watch your filter closely to see if this is the case, and if it is, simply add some water to your aquarium so that it is at the right level to cover the filter outlet. That should prevent it from causing more bubbles appearing in your tank. 

Bubbles in your Betta Fish tank

Keepers of betta fish have also noticed increased bubbles in their tank from the heaters installed.  Cold water is capable of holding more oxygen than warm water, and it is not uncommon to notice the formation of bubbles in your aquarium after you turn it on. As the heater does its job and heats up the tank, you will notice that the bubbles slowly will start to disappear. These bubbles formed in this way are harmless to your fish and your tank setup.

 Betta fish themselves are bubble nesters, and owners of male betta fish will sometimes notice them building a nest of bubbles on the surface of their aquarium. This is nothing to worry about, and can indicate that your male betta is happy and healthy. It is perfectly fine to destroy a bubble nest a Betta Fish has made as long as it doesn’t contain eggs. It is better to have a clean tank than it is to salvage the nest. If your water is dirty, then your Betta Fish will be less likely to build another bubble nest. 

How to get rid of bubbles in your aquarium

If you notice that you have foam present in your tank, you need to consider first giving it a good cleaning. The foam is usually an indicator that your tank needs a deep clean. The foam is caused by proteins that are present in the water, and they stick to the bubbles, and coat them. This in turn, causes them to not pop and stay around in your aquarium. You will want to start by cleaning the substrate by removing any debris from the aquarium and using an aquarium vacuum. Then you will want to remove all the decor items and give them a good cleaning as well. Regular water changes, and monitoring your water parameters are an excellent way to notice any changes that may occur before they become a problem.

 As the saying goes, ‘An ounce of prevention is worth a pound of cure.’ This means that it is better to prevent a situation from happening, rather than trying to clean up afterwards. If you have a routine cleaning schedule and maintenance checks on your aquarium setup, that is better than diagnosing problems as they arise later on. Gravel cleaning, filter maintenance, regular water changes, and monitoring the water parameters are all essential for the health and happiness of your aquarium.

Why are my fish blowing bubbles?

All fish breathe oxygen in the water through their gills, and all fish need proper aeration to survive.  If you notice that your fish are going to the surface of the tank and it looks like they are blowing bubbles, it is an indicator that your fish are not getting enough oxygen from their environment. It is also a sign that their water is loaded up with chemicals that are toxic and harmful to fish like chlorine and ammonia. It is important to monitor your fish from time to time and observe them for signs of distress. This can be corrected by cleaning your tank, and performing regular water changes.

Why does my fish have bubbles on it?

Fish can catch a disease called 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.

All bubbles aren’t all bad!

It is natural in an aquatic environment for bubbles to form, and you will always see bubbles in the water. In fact, not all bubbles in your tank are bad. Some hobbyists use bubbles for decoration. Some aquatic decor even have bubblers built into them, such as air stones that create a trail of bubbles that rise up to the surface. Those small bubbles help water move through the aquarium, and be very beneficial to your aquarium setup.

If the tank has a hanging filter, that will also create a small stream of bubbles. If you find that your tank has bubbles, and they aren’t sticking around for very long, the chances are that your bubbles are not going to be harmful to your aquarium setup.

Fish Laboratory

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

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