Why do betta fish make bubbles?

In this blog post, we will answer the question “Why do Betta fish make bubbles?” and also cover Betta fish reproductive characteristics.

Have you ever wondered why sometimes there are some bubbles in your Betta fish aquarium? Betta fish make bubbles in clusters on the water surface. These clusters are called bubble nests and can cover a great part of the surface of the tank or have only a few bubbles floating in small packs.

Why do Betta fish make bubbles?

Male Betta fish normally build bubble nests to attract females as courtship and potential mating, as an attempt to convince her he is a good match. It is known that this behaviour of making bubbles and building nests is instinctive. Thus, sometimes even a single male Betta fish may prepare bubble nests without having a female around. 

Fish species that build bubble nests are called aphrophilus. The nests, like any other nest, are built to lay the eggs and keep the young safe.

In natural environments, Betta fish live under conditions of water that are not favourable for hatching eggs. Thus, the presence of bubble clusters creates good conditions and safety for the hatchlings, with enough oxygen and free from the water flow, once they are limited swimmers.

How do Betta fish make the bubbles?

Betta fish owns an organ called the labyrinth. This organ allows the Betta fish to supplement their oxygen resource, by regular air-breathing. Male Betta fish use this organ to supplement their breathing and also for making bubbles. These bubbles, which are used to build the nest, are wrapped by a mucous layer. This mucus makes the bubbles last enough on the water surface. 

Can female Betta fish make bubble nests?

Although female Betta fish also possess the labyrinth organ, they are not capable of building bubble nests on their own. They are capable of producing bubbles, however, they only provide support and assist the male in building their nest. However, it is common that females produce some bubbles on the water surface as a result of air escaping, once they get their oxygen mostly from the surface air.

How to encourage a Betta fish to make bubble nests?

Although sometimes building a bubble nest is an instinctive behaviour of male Betta fish, encouraging its construction is recommended only in case you are planning to breed Betta fish. Some tank conditions may stimulate the Betta fish to start making bubbles for a nest:

–       Controlled water flow;

–       Floating items;

–       Temperature;

–       Water quality;

–       Stress-free environment;

–       New individuals.

Controlled water flow

Calm and gentle water flow is important due to the natural characteristics of the Betta fish. In the wild, they inhabit shallow waters, ponds, and slow-moving currents. Thus, reducing the splash zone of the air pump and its strength is important to keep the bubble clusters and eggs and hatchlings safe.

Floating items

Floating plants, leaves or any other floating item may stimulate the male Betta to deposit its bubble under. These items provide a barrier for the water current and keep the bubbles together.


Betta fish inhabits tropical areas, consequently, the temperature is also an important environmental condition for building bubble nests. Humidity and temperatures between 78 and 82 degrees Fahrenheit help the bubble to last longer and provide a safe nesting place.

Water quality

It is also important to keep the water change regime and cleanness. You can use a spoon to take the bubbles away when cleaning the tank, and after that, you place them back to the water surface gently.

Stress-free environment

Providing hiding spots and plants keeps the Betta fish calm and safe. A crowded tank will stress the individual and may provoke aggressive behaviours as described in “Why do Betta fish fight?”.

New individuals

It is recommended to encourage a Betta fish to build bubble nests only for breeding purposes. Thus, presenting a healthy and conditioned environment for breeding females will stimulate the male to make bubbles to build a nest. The female presence will motivate the courtship behaviour.

What if a Betta fish never build a bubble nest?

You do not need to panic if your Betta is not building a bubble nest. It does not mean that your Betta fish is unhealthy or unhappy. Male Betta fish start making bubbles for a nest when they reach sexual maturity, which means that not matured Betta fish will not build nests. Another possibility is that the male Betta fish may not be interested in spending energy on building a bubble nest at that time.

The bubble nest construction can be related to many other factors besides health and happiness, such as:

–       Sexual maturity (age and health);

–       Water flow/Current;

–       Water quality and Cleanliness;

–       Temperature and tank humidity;

–       Floating items.

Sexual maturity

Male Betta fish usually reach their sexual maturity around the age of four months. The breeding window for a male Betta fish is normally between four and twelve months old. If your Betta is younger than four months or older than twelve months, probably, it is not going to build bubble nests.

Water flow/Current

A strong water flow or current generated by the air pump in the tank normally makes it difficult for a Betta fish to build a bubble nest. This is because the current may carry the bubbles apart or even destroy them.

Water quality and Cleanliness

The quality of water and cleanliness of the tank can also influence bubble nest building. Smaller tanks normally need to be cleaned more frequently. pH levels are also important for Betta fish health and consequently their reproductive behaviours. Poor water quality and uncontrolled pH levels, also make it more difficult for Betta fish to make bubbles and build a nest.

Temperature and tank humidity

Betta fish are tropical fish, thus, it is important to keep the temperature between 78 and 82 degrees Fahrenheit. Trying to set a heater and a thermometer will help to maintain ideal temperature conditions, and consequently the thank humidity. High humidity levels will help the bubble maintain for longer periods. If conditions are not ideal, it might become difficult for Betta fish to establish their bubble nests.

Floating items

Having floating items in your tank may also stimulate Betta fish to build bubble nests. They frequently use floating items as support or barrier to producing their bubbles for a nest. The absence of items like these or floating plants may make bubble nest building difficult. 

What happens after bubble nest building?

After convincing the female he is a good match and mating, the eggs are free in the water. Female Betta fish do not get pregnant, they liberate the eggs in the water column, where they will be fertilized. The male carries egg by egg carefully to the bubble nest, where they will be kept until the babies become better swimmers. Male Betta fish are responsible for the nest and parental care.

The hatch occurs 2 to 3 days after the fertilization, and the surface tension protects the hatchlings from being carried away by the current. During this period, if any egg or the fries fall from the nest, the male keeps picking them up and carrying them safely back to the nest.


We focused this blog post on answering the question “Why do Betta make bubbles?” We understood more about Betta fish reproduction and bubble nests. This post outlined these reasons why Betta fish produce bubbles on the water surface and bubble nests building in detail and scientific behavioural explanation.

Frequently Asked Questions (FAQs): Why do Betta make bubbles?

How often does a Betta fish make a bubble nest?

Male Betta fish do not have a defined interval to build bubble nests. They will make bubbles when they feel it is necessary and under ideal conditions for reproduction. If you remove the bubble nest, they will make another one without an issue. Thus, you may see bubble nests many times a year. However, if your Betta fish is not making bubble nests, do not worry, it does not mean that your Betta fish is sick or under bad conditions.

Should I remove the Betta fish bubble nest?

If you are planning to breed Betta fish, you definitely should leave the bubble nest the male built. However, if you do not plan mating Betta fish, it is not an issue if you remove the nest built. Although, you can find a new bubble nest a few days or even hours later. However, you should be sure that there is not a single chance of eggs or fries existence on that bubble nest. If you remove a nest with eggs or fries, you will lose the offspring.

What if I accidentally destroy a Betta bubble nest?

Commonly, Betta fish make bubble nests right after the water change and tank cleaning. The quality of water and other water parameters are important for a successful Betta spawning. Thus, the male will build new nests under favourable conditions. So there is not an issue if you remove or destroy an empty Betta fish bubble nest. However, if your Betta fish have spawned and the eggs or fries are occupying the bubble nest, destroying the nest will probably kill the offspring. So, be careful when dealing with a Betta fish bubble nest.

Is my Betta fish happy because it has built a bubble nest?

Not really. Some people believe that the presence of bubble nests means the Betta fish is happy. However, it may not be true. Few Betta fish will start building bubble nests for no visible reason, as an instinctive behaviour. Occasionally, under specific conditions, the male Betta fish might make bubble clusters to establish territory over another male. 

How long do betta bubble nests last?

Normally, if we consider favourable conditions for reproduction success, the bubble nest will be kept and maintained by the male Betta fish until the fries gain control of swimming. The maintenance is making new bubbles and picking up eggs or hatchlings if they fall. The eggs occupy the nest for 2 or 3 days, and the fries will stay for 2 weeks more, approximately.

How many eggs can a Betta fish lay?

Betta fish normally can lay between 30 and 40 eggs during each spawn. However, in some special situations, they can lay up to 500 (five hundred!) eggs.

If you have any questions or comments please let us know!


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