If you notice your pet betta playing with air bubbles or a foam-like film on top of the betta tank, do not panic. It is normal betta behavior. This foam film is called a bubble nest.

We decided to explore the truths about bubbles in betta fish tanks. This article examines why, when, and how betta fish make bubble nests and what to do next to ensure everything goes well.

Let us begin this exciting journey with how they look?

How do Bubble Nests Look

how betta fish make bubble nests

The above image is of bubble nests shared by betta fish owners. Every nest looks different but is on the top level of the tank in areas with no/the least water current and anchored to some support.

It may simply form a single line on the tank glass, consist of large bubbles (as in the first image from the left), or look foam-like (the other two nests shared above).

The size, shape, spread, and thickness of the nests vary according to the age and personality of each betta fish.

Why Do Bettas Make Bubble Nests

The natural habitat of bettas consists of shallow, murky, muddy waters. They can survive in it due to a lung-like organ called a labyrinth, which enables them to breathe oxygen from the air if the water is less oxygenated.

A male betta instinctively makes a bubble nest to:

  • Announce he is willing to mingle.
  • Indicate his ability and willingness to protect and care for the fertilized eggs/fry(s).
  • Display his territory. A large (thick/well-spread) nest suggests better status and vice versa.
  • Impress/attract a female partner with his nest-building skills.

Female bettas who are ready to mate select their partners depending on the nests they build, physical attributes (like color, size of fins, vigor, aggression, etc.), and compatibility during courtship. A female betta may swim away and hide from the male betta if unwilling to pair.

Sometimes, she helps the male partner in nest-building, expressing eagerness to mate. So, do not be surprised if you find a pair engaged in the activity.

This nest-building instinct continues in captivity too.

Why Are Eggs Kept in Bubble Nests

Fertilized Eggs and newborn fry(s) cannot survive in murky waters with less oxygen.

Hence they are placed in the nest by the male betta. Each bubble has enough oxygen and moisture for the egg to hatch and grow till the fry(s) swim freely. Besides, it is easy for the father betta to guard all the eggs (from predators/drifting away) in a single nest.

When Do Bettas Make Bubble Nests

Each betta has a personality that influences his nest-building timing.

Ideally, a male betta makes the bubble nest to find a mating partner. However, in some cases, noticing a female betta swimming around may trigger the male to build it. Some bettas may make the nest after mating with their partners, while a few initiate it when the females lay eggs. Some bettas do not build a nest at all despite mating.

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How Do Bettas Make Bubble Nests

A male betta builds a nest at the top surface of the tank to ensure the eggs remain well-aerated and anchors it under floating plants, wood logs, leaves, hanging roots, aquarium walls, etc. These nests may even float freely on the water.

The male betta uses his labyrinth to blow air bubbles in the water on the top of the fish tank. The saliva coating strengthens/prevents them from bursting. Post that, he brings them together to bind with his saliva, completing the nest.

He guards the nest vigilantly (from predators/tank mates) before mating and continues guarding the eggs till the fry(s) swim out. He may even starve for weeks while on duty.

Watch this step-wise nest-building process.

What to Do Next

If you notice your male betta fish blowing nesting bubbles, avoid disturbing him. He will not appreciate distractions.

Avoid breaking the foam-like bubbles in your betta tank. It can upset the male betta big time! He recognizes the person who destroyed his nest and will refuse food from that person in protest or flare his gills in aggression. Besides, it also impacts him psychologically if he does not get the environment to build his nest.

Encourage your betta to build a nest as follows:

  • Feed him a high-quality diet as he consumes a lot of energy in nest-building.
  • Avoid breaking the nest while performing periodic water changes or stop partial water changes, as it will impact all fishes in the tank.

Remove the water gently from a safe distance from the nest. Insert a thin water tube (away from the nest) and lower it to ensure minimum disturbance at the top. Add replacement water slowly.

  • Many breeders gently scoop the nest into a broad mug with some aquarium water. Perform water changes, and release the scooped nest back into the aquarium.
  • Alternatively, move the nest-building male betta to a separate breeding tank. Once the bubble nest is ready, add a pregnant female betta fish to the breeding tank.

Feed them a high-quality diet (like live bloodworms, brine shrimps, etc.), as mating and spawning require a lot of energy. Allow them to mate. If the female betta refuses to pair, try pairing him with another female betta.

  • Maintain the aquarium/breeding tank parameters. A temperature of 78-82° F, pH of 6.5 – 7.5, and soft to medium water (hardness). Use a heater if need be.

What Happens Next – Mating and Fry Care

  • The male betta will chase the female betta. The male betta will embrace the female (as if hugging) several times. These hugs will pressurize the female betta’s abdomen, squeezing her eggs out in the water after each hug.

The male betta’s hugs are so tight that they may damage the mother betta’s internal organs. Many female bettas die after spawning due to this reason.

  • Male betta will fertilize the eggs with his sperm. Collect them into his mouth and place them neatly into each bubble in the nest.
  • Once the mating is complete, place the female betta back in the main aquarium before she eats her eggs due to a lack of parental instinct.
  • The male betta gets aggressively protective about eggs and will not tolerate even the mother betta around.
  • He rigorously guards the nest for a week until the hatched fry(s) swim out from the nest.
  • Once the fry(s) swim free, remove the father betta immediately, as he might start eating his fry(s).
  • Using a breeding tank is better as it makes it easy to transfer the mother and father bettas. Besides, it will double up as a tank for the newborn fry(s).
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It will be challenging to locate and separate tiny fry(s) individually before they fall prey to adult fishes/parents.

  • Learn more about fry care till they grow into adults.

The below footage provides a quick overview of the journey from mating to fry care.

Frequently Asked Questions (FAQs)

Why is my betta fish not making a bubble nest?

Listed below are some of the factors you can check:

  • Many betta species (scientific name Perciformes) are mouth brooders (like Betta Mandor, Betta Picta, etc.). They nurture the eggs and fry(s) in their mouths instead of building nests. Betta Brownorum breeds in nests/mouth-broods randomly. Check if your betta is a mouth brooder.
  • Bettas are sexually mature from the age of 4 to 12 months, after which they stop breeding, as the quality of their offspring becomes poor. Is your betta too old to breed?
  • Maintain the following water parameters to encourage nest-building:

Water temperature – 78 – 82° F
pH – 6.5 – 7.5
Water Hardness – 5 – 20 DH

  • Bettas prefer places that can hide and anchor their nests. Adding floating plants/wooden logs, leaves, hanging roots, etc., in the aquarium may provide a conducive environment.
  • Your betta will not build a nest if the top of the tank has a water current that might scatter/break his nest. Keep the current slow and minimal on the top.
  • Check if he is unwell. Look for physical signs (wounds, nipped fins, infection, etc.) or diseases (like white spots) on the body. Consult a vet for a correct diagnosis and treatment.
  • Your male betta may feel threatened to build a nest thinking another competitor is blowing more bubbles than him if your aquarium filter creates tiny bubbles (the size of betta fish nesting bubbles). Keep the filter bubbles relatively larger.
  • A well-managed aquarium induces nest building because your betta feels happy, healthy, and safe. Notch up your tank management.

We hope this helps you.

Can betta fish eggs hatch without bubble nests?

Yes. As discussed in point (1) of question A, some betta species are mouth brooders. Their eggs hatch without a bubble nest.

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Some bettas mate but do not bother to make a nest. In such instances, the eggs scatter in the tank bottom. They may still hatch if incubated artificially, as explained below.

Remove unfertilized eggs from the floor immediately before they rot. Move the fertilized eggs to an artificial nest made from a foam/sponge like an egg crate, with a small divot for each egg. Float it on top of shallow water in a tank to keep the eggs moist.

Maintain water parameters specified in FAQ (A), point # 3, with a slow water current away from the eggs to keep them aerated.

Even without artificial incubation, leaving the fertilized eggs in a tank with shallow water, with apt water parameters and current, may still result in some hatchlings swimming free.

The survival rate might be lower without a bubble nest, but betta eggs can hatch without a bubble nest.

Can pregnant betta fish make a bubble nest and lay eggs in absence of a male betta?

Female betta fish carry unfertilized eggs inside their bodies between 4 to 12 months of age (maximum 14 months) till they are sexually mature.

If there is no male betta, the female reabsorbs her eggs and creates them again. However, it is not uncommon to see female betta fish laying eggs instead of reabsorbing.

At times she eats her eggs after releasing them. A few betta owners have reported their female betta fish making a bubble nest and placing her eggs in it. Post that, she destroys the nest and eats the eggs.

If the female betta does not eat her eggs; or leaves the bubble nest with eggs as it is, owners remove the unfertilized eggs from the tank bottom/destroy the bubble nests, and remove the eggs before they rot. Female-only betta tanks demand extra care and cleaning.

Thus, a pregnant betta fish may lay eggs and make a bubble nest without a male betta. But these eggs cannot fertilize without him.

Watch a female betta laying her eggs and eating them simultaneously.

Final Thoughts

There is a myth that male bettas blow bubbles when they are happy. However, the truth is that they build nests when they desire to mate. Ill health may refrain some male bettas from nest-building. But an overwhelming desire to mingle supersedes other concerns for a few.

If you accidentally break a bubble nest, do not worry. Your betta fish will rebuild it quickly.

Now that you know everything about betta bubble nests, you can support your male bettas better by providing the right environment to thrive.

We wish you a happy grand parenting time!

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About the Author

Victoria Lamb

Victoria is a freshwater aquatics specialist, fish keeper, and amphibian enthusiast. She has had more than 6 years of experience caring for aquariums and keeping several fish species, and her home boasts of 3 aquariums and a garden pond. Her goal is to educate fish owners on raising healthy and happy aquatic pets. Career Highlights:…

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