What’s the betta bubble nest?

One day your betta is fine and playful, then the next day you wake up to a tank full of bubbles! But why are they there? You might question yourself whether something is wrong with your fish, the bubbler, or even if it is already time to clean up the tank.


In this post, we will talk about these bubbles, why are they in your aquarium, where do they come from, if they present a risk to your betta, and what to do in case you find one in your betta’s tank.

What’s the betta bubble nest?

Betta fish actually make the bubbles you see in the aquarium! So, you do not need to worry that something is wrong with your betta, or that you need to do some extra cleaning on your tank. The bubbles are the result of the male betta fish building its nest. Female bettas do not build a bubble nest.

How is the betta bubble nest built?

Bettas are anabantoids. This means that they can breathe atmospheric air because they have an organ called the labyrinth, which is similar to primitive lungs. In their natural habitat, the labyrinth helps them increase their oxygen supply in low-oxygen environments, such as rice paddies and marshalls, for example.  Male bettas also use this organ to bubble nests. They blow bubble by bubble on the water surface coating each one of them with their saliva to make sure they do not burst. The saliva also forms a layer that keeps the bubbles together. 

Once the bubble nest is built, the male betta will defend it fiercely, even engaging in fights if there are other male bettas or even other fishes in the aquarium.

Why do bettas build their bubble nest?


In nature, building a bubble nest is the first step in courtship and mating for the male betta. After the nest is finished, the male betta will look for a female to mate. If there is a betta sorority in the tank, the female leader will spawn if she accepts the courtship. If there is another male betta in the tank, they might fight to get the female betta’s attention. 

It is common for the male betta to build a bubble nest even if alone in the tank. The size and the thickness of the nest will depend on their personality. If you add a female Betta to the tank, monitor the pair carefully. They might fight during courtship. 

In case of a fight, be ready to separate them. In case the female betta is not ready to spawn, the male might bite her which will lead the female to feel very stressed. However, if you see that the female starts swimming together with the male, then they are good to go. When the eggs are fertilized in the water column, the male betta will pick them up, and spit them into the nest.

The fertilized eggs hatch in a couple of days, developing into fry. The fry stays close to the nest for about two weeks. If any eggs fall from the nest male bettas pick them up and secure them back into place. The debris used to secure the nest combined with the surface tension of the bubbles protects the fry until they are ready to swim. The male betta protects their fry from nest intruders or potential predators. When a curious fry wanders away, the male betta will carry them back to the nest.

It is the male betta’s job to tender for its nest and fry. Apart from releasing the eggs to be fertilized, the female bettas do not tend their fry. They might help the male build their nest by bringing some weeds or driftwood to the male betta. But that is all.

How frequently do bettas build their bubble nest?

The frequency that bettas build their bubble nest actually depends on the individual fish. Some fish build it on a regular basis, while others can build their bubble nest in a matter of weeks or even months. Some bettas do not build a bubble nest at all!

A sudden change in the betta’s environment can also induce bubble nesting. This could be due to changes in the tank’s temperature, layout, introduction or removal of decorations, and the addition or removal of a tank mate. Building a bubble nest is a way to propagate their species and avoid extinction.

Does bubble nest mean that my betta is happy?

No, a bubble nest does not equal the happiness of a betta. Building a bubble nest will depend on your betta’s temperament. Some bettas are always building nests, while others will not build any. Other bettas are not really interested in building nests and some will only build a nest when spawning has begun. 

Hence, if your betta occasionally builds nests, or does not build at all it is alright. It does not necessarily mean that your betta is unhappy or unhealthy. So, do not worry if you do not see a bubble nest in your betta’s tank. You might check the water parameters and temperature just in case though. The lesson here is that every betta is very particular when it comes to building its bubble nests.

Sometimes, bettas can blow a few sporadically bubbles on the water’s surface. This also does not mean that there is something wrong with your fish. It might just have started building its nest.

Now, if you happen to see that the bubbles are floating scattered on the water surface, it could be the result of a betta breaking the nest apart when it swims through it. That also does not mean that your betta is sick or unhappy.

However, you need to pay attention to your betta’s overall behavior. This is because bettas are able to blow bubbles even when they are sick. If you see that your betta is lethargic, keeps hiding, loses its appetite, and still blows bubbles, then you might suspect something is wrong. Do not wait long and seek the proper treatment for your fish.

Why does my betta never build a bubble nest?

Although not building a bubble nest could also be a common behavior of a male betta, there might be some reasons behind your betta failing to build a bubble nest. 

The overall health and the age of your betta can influence the frequency that they build their bubble nests. Like it was mentioned above, if your betta is lethargic, hides most of the time, and does not show up during mealtimes, it might be sick. Seek proper help for your betta.

Maybe, it can be that the current tank setup is not appropriate to your betta. Check the water quality, pH, and temperature. Bettas are tropical fish and do not do well in cold water. Also, if the tank is not clean and the flow is strong, bettas might get stressed which hinders them from building their bubble nests. 

Lastly, lack of enrichment in the tank such as plants, driftwood, caves, and other decorations can make your betta feel depressed which decreases the chances of him building a bubble nest.

Cleaning the betta’s tank without destroying the bubble nest

Sometimes you need to clean your betta’s tank and you find a bubble nest right on the aquarium’s surface. You might wonder what to do, or how to clean the tank without destroying the bubble nest.

There’s no real need to remove your betta’s bubble nest. But if you want to remove it to clean the tank is perfectly fine. Just make sure that you carefully remove the bubble nest with a ladle or a plastic cup, and put it back when the tank is cleaned. If you accidentally damage the nest and decide to remove it completely, do not worry. Your fish can build another one in no time if he wishes to, as long as they have a clean tank. 

Be extra careful with the bubble nest if you are trying to breed your bettas or if you see fertilized eggs and fry in the nest. Unfortunately, both eggs must be in the nest in order to hatch. When an egg falls off the nest, the male betta will pick up the egg and return it to the bubble nest. In the case of the fry, they also need to be in the nest until they are able to fend for themselves. If a fry wanders out of the nest, the male betta picks it up and returns it to the nest. The bubble nest keeps them safe from predators. The fry usually stays in the nest for about a couple of weeks, taking all their nourishment from the water surface.


Bettas are fun and beautiful fish. They can surprise us with bubbles nicely arranged at the corner of their tank, around a floating plant, or at the surface water. These are called bubble nests and are one of the first steps of betta’s spawning.

These nests are built with the help of the labyrinth, an organ that resembles primitive lungs and enables bettas to breathe atmospheric oxygen, as well as the oxygen dissolved in their water tank. They can pull and release the air in the form of bubbles and its saliva will keep them all together.

This oxygen-rich environment is where the female betta will deposit the fertilized eggs after mating. Then it will be the male betta’s job to defend the nest from any threat they may be faced with. When the eggs hatch, the male betta also tends to its fry until they become big enough to fend for themselves.

However, building a nest is not intrinsically connected to mating. A lot of male bettas do build their bubble nests without having a female betta to mate. Bettas will build their bubble nests when they have a safe and clean environment. 

A tank with enough room for them to build their nest, the right temperature, water parameters (pH, ammonia levels), filled with plants, driftwood, and decorations might do the trick so your betta builds its nest. If you want to breed bettas, you can then introduce a female so they can spawn.

When properly cared for the bettas are happy, more active, and less stressed. Thus, the chances of building a nest increase.  But if you do tend for your betta and it still does not build a bubble nest, do not worry. It will be happy and feel safe all the same. 

Did you know about bubble nests? Do you have male bettas that have built a bubble nest? How often does it build? Please,  share your experiences with us, make comments and ask questions. It is always a pleasure to read your opinions!


Barrington, K. n.d. The right way to care for Betta fish. Talkfishy.com. 45 p.

Bronstein, P. M. (1980). Betta splendens: A territorial note. Bulletin of the Psychonomic Society, 16 (6), 484-485.