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Why Do Bettas Make Bubbles (A guide to betta bubble nests)

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Betta fish have unusual behaviors, such as blowing bubbles, but why do bettas make bubbles? This article explains why bettas make bubble nests and why they are so important. I’ll also cover how betta fish blow bubbles so easily and the many reasons why they behave this way.

During mating season, male bettas blow bubbles to construct a nest. The bubble nest attracts a fertile female mate, and after procreation, the male betta places the fertilized eggs safely in the nest, where they are protected. The bubble nest is guarded by the male until the fry has hatched.

why do bettas make bubbles at the top of the tank

There are other reasons why betta fish blow bubbles, such as marking their territory and warning other male bettas away. The bubble nest is used to protect the young betta fry before they hatch and for a few days after.

Make sure to check out our Betta Fish Care Guide.

What Is A Betta Bubble Nest?

Floating debris is usually covered with bubbles by a male betta to create a bubble nest. It is the only thing males produce from their sperm-producing organs or papilla.

The bubbling is caused by the rapid beating of specialized muscles (opercular cilia). These bubbles are used to attract a mate and are an important part of the mating process.

A betta can take up to three hours to make a bubble nest, but it is often finished within an hour if a female is present.

Image of a male betta making a bubble nest.
A male betta blowing a bubble nest

Why Do Betta Fish Make Bubble Nests?

When a betta fish builds a bubble nest, it is called “attempting courtship.” The process of building a nest is only part of the courtship behavior, but it is very important for the betta to get it right. A female betta will inspect the nest closely before choosing to mate.

A bubble nest holds the fertilized eggs laid during mating, and it protects the newly hatched fry. The bubble nest provides protection against predators, fungi, and bacteria that might otherwise hurt the eggs and fry.

Bubble nest building is usually done throughout the day and is typically built on floating objects or plants within an aquarium.

Why Do Male Bettas Blow Bubbles?

People often ask why male betta fish blow bubbles, and the truth is that both male and female betta fish can blow bubbles.

A male betta will build a bubble nest to attract females as part of the courtship behavior. He goes through several stages of showing off his beauty before mating with her.

Males bettas can become aggressive if other males come too close to their nest, and sometimes males create nests to keep other males away from their territory.

How Do Bettas Build Bubble Nests?

While the male betta creates its bubble nests out of very small air bubbles, the actual nest is usually covered with a fine substrate (such as the fine-grain sand found at pet stores). This allows a smooth surface for the nest to form on without being too bumpy or rough to hurt the eggs or fry.

Bettas have a labyrinth organ that enables them to breathe air from the atmosphere and expel bubbles. It is located just below the gills. When the betta uses this organ, it widens to take in oxygen. It then contracts to expel that oxygen, creating a bubbling effect.

Male betta fish go through several different stages of bubble nest building before it’s finished.

First, he prepares a spawning site to construct a bubble nest. This is done by gathering fine grains of substrate in his mouth, bringing it to the surface where he blows it out into a pile on top of the water. The finer the substrate, the better it will work as a base for the nest.

A sticky saliva is mixed in to bind the substrate and bubbles together, and sometimes, the male will use leaves or other types of floating debris to anchor the nest in place.

Next, the male betta fish will expel the air from his mouth, forming bubbles in the substrate pile and spreading it out to give himself room to blow more. He may also pick up larger objects with his mouth (like pebbles or leaves) and place them on the pile to better shape the bubble nest into a small dome.

The male betta will keep blowing air into the substrate until the nest is completed. He may blow small amounts of substrate out as he works, but most of it remains inside the nest with just a few “windows” open so that more air can come in.

How Can You Tell If A Betta Is Building A Bubble Nest?

You can tell if a betta is building a bubble nest by looking at whether or not it is gathering substrate from the bottom of the tank or moving around with something in its mouth that could be either food or building material for a nest.

If your betta’s fins are flared and if he is swimming erratically and blowing bubbles near the surface, there is a good chance that a nest is under construction.

What Happens When The Bubble Nest Building Is Complete?

Once a male betta fish has built his bubble nest, he will go to the surface and flap his fins rapidly to draw attention to it. He may also circle the nest in full view of nearby female bettas that may be interested (he’s showing off).

I found the Youtube video below, which demonstrates how betta fish mate. It shows how a bubble nest can look and its use.

Betta fish placing eggs in a bubble nest.

At this point, the male will begin to feel very threatened if he sees another male near his nest. However, if there are other females around (and no other males), he may allow a female betta fish to swim into his bubble nest for inspection. If she is interested in mating with him instead of one of the other fish in the tank, she will go to the bottom of the bubble nest and lay her eggs.

If the female betta does not like the male, she will swim away and either find another bubble nest to lay her eggs in or lay them on plants in the aquarium.

Do Female Bettas Make Bubble Nests?

You may be surprised, but you can also find female bettas building bubble nests! Female betta fish usually build bubble nests when they are pregnant with eggs, and no males are present. Instead of using sperm-producing organs or papilla, females use their ovipositor to lay eggs. Laying unfertilized eggs are called “slug” eggs.

The female betta will go through the same stages as the male when making her bubble nest, gathering the substrate in her mouth to build it up and blowing air into it with her opercula muscles. The only difference is that a bubble nest made by a female betta usually doesn’t have much detail because she is not trying to woo any other female bettas.

While it is possible for both male and female betta fish to make a bubble nest, it is much more common for the male as it forms part of his mating ritual.

Should You Remove A Betta Bubble Nest?

There is no need to remove betta fish bubble nests after they have been built, however, some recommend removing them to prevent the male from becoming aggressive and territorial toward other fish when trying to protect their nests.

If your betta is in a tank by itself, you can leave the nest alone, but if it is in a community tank, you should monitor its behavior toward the other fish in the tank. If your betta’s aggression has increased, you should remove the nest.

Destroying A Betta Bubble Nest

You can remove and destroy your betta’s nest if you feel he would be happier without it. When removing the nest, be cautious since male bettas will become extremely aggressive about their home, even if it isn’t required.

There are also various opinions on whether or not a betta will be able to rebuild its bubble nest. Some believe it is very likely, while others say the male may never build another one.

Do Betta Fish Blow Bubbles When They Are Happy?

Some betta fish construct a bubble nest even when they don’t have a mating pair. Tank conditions need to be good, the water needs to be clean, and they will build their nests to signify happiness.

Betta fish may also blow excessive bubbles if oxygen levels in the water are low due to poor tank conditions, excess algae, overstocking, or other oxygen-depleting reasons. When there is a lack of oxygen, betta fish will breathe oxygen from the air.

Air-breathing is possible because of a labyrinth organ that I will discuss below. Oxygen from the air is not the same as the dissolved oxygen found in the water, and it creates lots of bubbles when expelled.


The betta fish bubble nest is central to the betta mating ritual. It is used to attract a mate and to protect the eggs before they hatch.

Bubble nest building is a natural behavior you can observe in your male betta. There are many instances in which a female betta will build her own bubble nest, although she may not make them as elaborately as the male.

If you want to encourage your betta to make a bubble nest, you must ensure that you have set up your betta tank correctly so it feels comfortable and happy in its environment.

Not all bettas will build a nest, so if you find one in your betta tank, you should consider yourself lucky! Keep your eyes open for the other stages of the mating ritual as well! If you have a male and female betta living together, keep an eye open for some betta fry as well.

If you have a breeding pair, even if it was not your intention to breed your betta, it may be useful to have a breeding tank, especially if you keep your betta fish in a community tank. You could also start a betta sorority tank with several females.

You may find you are more successful in breeding by using a separate tank, which will also protect the newly hatched young from larger fish.

Frequently Asked Questions

Bettas make their bubble nests when they feel ready to breed. You can increase your chances of getting a betta to make a nest by providing floating plants and surfaces for him to attach his nest to and ensuring the water conditions are perfect.

You should remove a bubble nest if your betta fish becomes overly aggressive and territorial towards other fish in the tank. Male betta fish instinctively protect their nests from other fish.

Nothing will happen if you remove your betta’s bubbles nest, however, he will probably try to build another. Bubble nest building is a good sign that your betta wants to mate or is happy in its tank.

A betta fish that doesn’t make a bubble nest is not interested in mating or doesn’t feel the conditions in the tank are good enough to breed. If you want your betta fish to breed, you should create the perfect conditions, including water temperature and other parameters.

During the breeding season, you can’t do anything to control your betta’s instinct to build a nest and find a mate. Because the behavior is instinctive, you should let him get on with building his nest.

The bubbles that betta fish make on the top of the water are usually bubble nests, however, your betta fish may just be blowing bubbles to pass the time or breathing oxygen from the air outside of the tank due to a lack of oxygen in the water.

You may find your make betta fish making a bubble nest without a female when he is happy in his tank. A betta making bubbles is a natural instinct, as is creating a nest, which will occur when your betta is relaxed in its environment.

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