Are Microbubbles Bad For Fish?

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As an aquarium hobbyist (new or long time), it is no doubt you must have done proper research in finding what is suitable for your fish. From the size of the tank to the best choice of light and aeration system, the right temperature, and decorations to add more beauty to your aquarium and provide a hiding place for your finned friend. 

You can take care of your aquarium regularly, however, you started noticing some strange bubbles in your water. What could these bubbles be? Why do they appear all of a sudden? Could they be harmful to your fish?

As a true hobbyist, these and more are some of the questions that will run through your mind. This article will give you a detailed explanation of why these bubbles form suddenly, why they form, and if they are bad for your fish.

Are Microbubbles Bad For Fish?

It all depends on how much the microbubbles are. A moderate amount of microbubbles are not harmful to your fish. But as the popular saying goes, too much of everything is bad. So also too many microbubbles are bad for your dear fish. It can be fatal. 

It is normal to have microbubbles in some situations, and there are other situations where you will need to remove your fish immediately. Microbubbles as a result of bubbles nest are normal and there is nothing to worry about.

When the microbubbles in your tank are a result of situations like an excessive amount of ammonia in the water, then you will need to remove the excess ammonia as soon as possible. Excess ammonia is very toxic to your fish and if immediate action is not taken, your fish can most likely die from the toxicity.

What Causes Microbubbles In Your Aquarium?

Microbubbles don’t appear in your tank just because. Different factors can cause too many microbubbles in your tank. Some of the common causes of microbubbles are;

– Lack of Proper Maintenance

Always clean and remove debris and food remnants to avoid them causing a chemical imbalance. If you don’t clean your tank properly, the bubbles trap the dirt in the water and this does not allow them to pop. 

– Change in Temperature

If you pay attention to your tank after a water change, you will notice some microbubbles in your tank. This is a result of a temperature difference.

When the temperature of the water you add is cooler than the one inside, there are going to be microbubbles all over the glass. These bubbles are harmless to your fish and plant and will disappear once the water becomes stabilized.

– High Level of Ammonia in the Water

A high level of ammonia in your water is bad for your fish and the entire ecosystem. Ammonia accumulates most times as a result of disturbance to the nitrogen cycle. Excess ammonia results in too many microbubbles.

– Wrong Filter Size

Having a filter smaller than your tank size will create microbubbles. The filter wouldn’t be able to maintain the balance of oxygen in the tank hence the microbubbles as a result of increased oxygen level.

– The Use of Some Medications

Sometimes your fish will need medication. Medicines like Pimafix can create bubbles when added to water because of the change in the thickness and density of the tank water. These bubbles are clean and transparent in appearance

– Bubble Nests

Your finned friend itself creates bubbles in the water. This is called a bubble nest and it is usually seen at the corners of your tank.

They consider the corners as a safe place to keep their eggs because most bubble nests contain fish eggs.

– Pearling from Plants

The process of photosynthesis produces oxygen, this oxygen can sit on the leaves of the plant forming bubbles.

It is a healthy sign your plants are growing and carrying out their activities, the bubble formed on the leaves is known as pearling.

– Too Many Fish

Overcrowding your tank with fish beyond its capacity will make microbubbles a common occurrence.

The increased number of fish means an increase in the amount of waste which will get to a point that surpasses the filter’s capacity. This will cause an increase in the oxygen level forming microbubbles in your tank.

– Bad Tank Location

Placing your tank directly where sunlight can get to it will create microbubbles. The direct contact of your tank with the sunlight increases the temperature which will in turn create bubbles.

– Biofilm at the Surface of the Water

When oil gets into your tank water, it can create oil films at the surface. Some fish food contains oil. Water and oil cannot mix, this will make the oil create a biofilm at the surface, and this will hinder gaseous exchange. This will result in microbubbles at the surface and in the tank itself.

– Soap

When you notice rainbow-like coloured microbubbles, it is mostly due to soap in the water. The most time during cleaning, the soapy water can mistakenly pour into the water and pollute it. This can be dangerous to your fish and the water needs to be drained and changed.

– Agitation

Agitation can form microbubbles, but they are temporary. Agitation can occur when changing your tank water or if you are using an air pump. This type of microbubbles is not harmful to your fish.

– Improper Aeration

When your tank is not properly aerated, there will not be enough oxygen for your fish to survive. The tank can get a lot of other toxic chemicals like chlorine which is toxic to your fish.

You need to always test your water to make sure these chemicals are maintained at normal levels. Adding a filter will help in aerating your tank and increase the level of dissolved oxygen in your tank.

Sometimes the appearance of microbubbles in your tank is harmful to your fish while some causes are not and will disappear on their own. Any cause that will pose threat to the well-being of your fish should be tackled immediately.

Are Too Many Microbubbles Harmful To Your Fish?

Yes, Microbubbles can harm or even kill your fish when it becomes too much. Just a few microbubbles are okay to keep your fish’s ecosystem in good condition. Too many micro bubbles lead to an increase in oxygen and other parameters of the tank. This can stress your fish a lot and can kill or fish if not cause serious harm to them. 

You need to keep a close look to monitor if there are too many bubbles in your tank. If you notice on time, then you will take fast action to prevent possible harm to your fish and even plants because too many bubbles are also harmful to your aquarium plants. It kills plants because the gaseous exchange between the tank and the atmosphere is limited. 


Microbubbles are not entirely bad for your fish depending on what brings about the bubbles. Bubbles as a result of bubble best are entirely safe or those caused due to change in temperature or agitation.

They disappear once the temperature of the tank becomes stabilized which doesn’t take long. Microbubbles due to excess ammonia are harmful to your fish and there is a need to reduce the level as soon as possible for the healthy benefit of your finned friend. 

Written by Justin Michaels

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