If you’ve ever looked at Betta Fish in the store or owned a Betta personally, you’ve probably come across a mystery: foamy bubbles near the surface.
You may have thought that the tank was in need of a cleaning or the air bubbler was working on overdrive.
However, there is a simpler yet much more interesting explanation: Betta Fish actually blow bubbles on purpose! But why are Betta Fish bubbles a thing and what does this mean?
Why Do Betta Fish Make Bubbles?
As it turns out, your Betta Fish is not sick nor is the water in need of cleaning! Male Betta Fish regularly blow bubbles into piles in the corner of the aquarium because they are nest building fish!
Most fish aren’t really good parents. They will meet briefly with their mates to release eggs and sperm, which then float freely along the currents until the baby fish hatch.
Some fish, such as Danios and Tetras, take this a step further by scattering their eggs among dense plants, where they (hopefully) stay hidden before hatching.
But even then, the parents quickly forget about their offspring and leave the rest to chance. A few fish, including Cichlids and Gouramis (which bettas are a type of) provide extra care for their eggs and fry. Instead of scattering them in the water or plants, they take the time to carefully build nests. They will even defend their eggs and young from rivals or predators that might try eating them!
Birds use twigs, leaves, feathers, and cloth in their nests. Mammals use hair and grass for theirs. But Betta Fish use the only material they can: bubbles from air and mucus. In nature, when the males are ready to breed they find gentle patches of still water full of weeds and other floating materials to stick their nests to.
Since bettas are found in rice paddies, clogged waterways, ditches, and slow-moving rivers, there are usually plenty of places to spawn.
Then, one by one, they blow bubbles on the surface that coagulate and form a layer that first time Betta keepers might find confusing but is completely natural.
Betta Fish Bubbles are like a foamy love nest for prospective mates.
Since bubbles are constantly lost the male will periodically blow bubbles each time he gulps at the surface for air (remember that Betta Fish are partial air breathers, thanks to their labyrinth organ).
Once the bubble nest has been built the male will then defend the spot from other males looking to build their own bubble nest. In the sticky heat of Southeast Asia, the shallow bodies of water that Bettas live in will start to evaporate.
They then get pushed into very close proximity with other males, which is when their famous fights erupt! Betta males have to be aggressive in order to defend the choicest places to raise their babies! So if you see bubbles in a Betta tank then you know that you’re looking at a natural behavior that male Bettas engage in!
What is the Betta Bubble Nest For?
Once the male Betta fish feels his bubble nest is complete he will start looking out for females to impress and rivals to drive away. The presence of a female Betta in the aquarium will also cause him to work on his nest in overdrive, preparing for their eventual courtship and mating.
If you do decide to add a female Betta to the tank, be very cautious and watch the pair carefully. Male Bettas can be very eager when first meeting a mate who is only just getting used to her new tank. Sometimes he will start harassing her the moment she hits the water.
And if she’s not immediately ready to spawn he may start biting her, stressing her even more. Hopefully, the presence of a female will encourage him to start working on making his bubble nest bigger. Since this takes time she will be able to develop eggs in the meantime!
Once the female is sufficiently impressed as to mate with him, the Betta eggs are fertilized in the water column, picked up by the male, and spat directly into the nest.
Over the course of 2-3 days the fertilized eggs develop and hatch into tiny baby Betta fish. The young fry are poor swimmers when newborn.
Fortunately, the surface tension of the bubbles combined with the weeds and debris collected around the nest provides plenty of barriers to keep the newborn fish near the surface until they are ready to swim. Male Bettas are excellent parents!
Other fish in the Gourami family either create bubble nests like Bettas or are mouthbrooders, carrying their eggs and young within their mouths until they are ready to live on their own.
However Betta Fish are the only ones that will create bubble nests even when kept alone.
Providing the Best Conditions for Betta Fish Bubble Nest
If you want to make bubble nest building less frustrating for your male Betta Fish then consider surface water conditions.
Still water is the most important because in nature Betta Fish are found in shallow ponds, rice paddies, ditches, and other slow moving and still bodies of water.
Even the splash zone created by a hang on the back filter can ruin days of careful bubble blowing. If you own one of these types of filters keeping your aquarium topped off will help minimize disruptions to the bubble nest.
Surface debris not only provides structure but also helps protect the Betta Fish bubbles from current. In nature, your male Betta would weave his bubble nest among floating plants, sticks, and leaves.
If you can provide floating plants like Hornwort, Elodea, or Crystalwort to anchor his nest to, your Betta Fish will find it easier to maintain his nest over time! In this Guide to Easy Betta Fish Plants I cover many options that help improve bubble nest stability.
Lastly, consider getting him some company! A female Betta, properly conditioned for breeding, will allow him to finally put that bubble love nest to use! A nearby male in a separate tank will also encourage some healthy competition along with occasional gill and fin flaring matches.
Do Other Fish Make Bubble Nests?
Betta fish bubble nests are the most common instance of this phenomenon. But believe it or not, Betta are not the only fish that make bubble nests! Nearly all fish in the Gourami family (family Osphronemidae) use varying mixtures of bubbles and floating plant matter to build nests for their eggs and babies. Common Bettas (Betta splendens), Dwarf Gourami, Blue Gourami, and other common aquarium species use the least plant material in their bubble nests.
Many of the larger species, including the Kissing Gourami (Helostoma temminckii) and Giant Gourami (Osphronemus goramy), may make a few bubbles as a sort of signal that they are ready to spawn. But they use nothing but twigs, leaves, stems, and other large pieces of plant matter rather than bubbles for their nests.
Many other Bettas are actually mouthbrooders! Rather than building floating betta fish bubble nests they instead collect the eggs and hold them in their mouths. The Common Betta is the most popular betta by far. But there are dozens of other Betta species. The Brunei Beauty, Betta Macrostoma, is becoming more popular with betta lovers due to its subtle colors, large size, and mouthbrooding behavior!
Hoplo Catfish (Megalechis thoracata) are also bubble nest builders. They are one of the largest members of the family Callichthyidae, which includes all of the super popular Corydoras catfish! Most Corydoras don’t build nests; it’s only the larger members of the subfamily Callichthyinae that do!
What Other Nests Do Fish Make?
Besides bubbles in a betta tank you may see other nests built by fish in the aquarium hobby! Cichlids are the other major nest builders. Instead of floating plants or bubbles they tend to clear away rocks, gravel, and sand to make small pits. Within these pits the cichlids will lay their eggs, usually on a hard surface like a rock.
After spawning one or both of the parents will watch over the eggs. Typically the female will fan the eggs while the male patrols the territory, chasing off any rivals or predators that get too close. Once the babies hatch they receive further parental care until they are large enough to fend for themselves.
Some cichlids, including Angelfish, spawn on vertical surfaces like Amazon Sword Plant leaves instead of cavities in the dirt. While they are normally quite peaceful even Angelfish can be aggressive, devoted parents for their eggs and fry!
Frequently Asked Questions about Betta Bubble Nests
Female Bettas never build bubble nests. Only male Bettas build bubble nests.
Betta bubble nests are a place for male Bettas to entice females to come spawn under. Once she spawns the eggs float into the bubble nest, to be cared for by him, even a few days after they hatch!
A Betta bubble nest looks like a foamy raft of small bubbles that can be anywhere from a few centimeters to a few inches in size. They are usually built at the corner of a fish tank or among plant leaves near the surface, where they are least likely to float away or be damaged.
Most fish in the Gourami family make bubble nests, as well as certain catfish! But Bettas are the most famous bubble nest builders!
Did you wake up today to find bubbles in your fish tank that has no air pump? Not to worry! If it’s a betta then it’s not a sign that your fish is sick.
He is merely trying to impress a potential mate by building a bubble nest. Betta fish bubble nests are entirely normal and a behavior that nearly all healthy betta males will engage in!