There are a lot of reasons someone would want to keep a betta fish. Also called Siamese fighting fish, bettas are fancy looking and colorful. They have personalities, too. And while they are not the most docile of fish—particularly around their own species—they make for a wonderful addition in bowls and tanks.
One thing you might notice after keeping a betta fish is that they display some quirks, like building nests made out of bubbles around the surface of the water. Some people describe these nests as foam on top of the water. In reality, these bubble nests are a display.
Here is everything you need to know about betta bubble nests, including how and why they happen and how to encourage a male betta to build one.
What Are The Bubbles At The Top Of The Fish Tank?
It sounds like you are looking at a bubble nest—a creation that serves as shelter for betta eggs. The bubbles are composed of saliva. The saliva is highly durable, so the bubbles won’t immediately pop.
This cluster of bubbles is a totally natural behavior performed mainly by male betta fish. If you see a betta bubble nest in the fish tank or bowl, you know you are doing a good job at fish keeping, because your fish feels happy and safe enough to think about setting up a home for eggs.
Why Do Betta Fish Build Bubble Nests?
A bubble nest is essentially a major step in the breeding process. Since betta fish are bubble breeders, meaning they keep their eggs within the bubble nest, the construction of one is a cornerstone of courtship. Since the male Siamese fighting fish is the one who initiates the process, he is the one who builds the nest, attracts the female, entices her to lay fertilized eggs, and then guards those eggs until they hatch.
Are Eggs Kept In The Betta Bubble Nest?
Yes, eggs are definitely kept in betta bubble nests—and for good reason. In the wild, betta habitats are usually dirty and full of danger. Think shallow, muddy puddles that are low in oxygen. When the eggs are secured within bubbles, it only keeps the egg sacs moist and protected, but there is also plenty of oxygen surrounding the growing babies. It is believed that is the main reason betta fish build bubble nests.
Furthermore, once a female betta fish releases her eggs into the build nest, she no longer has any responsibility. Female betta fish do not protect or raise their young. The male, however, will fight off potential perils and guard the bubble nest until the eggs hatch. If eggs begin to fall from the nest, for example, the male will gently gather them up and put them back inside the nest.
Eventually, the eggs hatch after a few days, but the fry (baby bettas) will remain within the bubbles until they are able to survive by themselves.
One of the questions that spawns from this peculiar habit is why betta fish build nests out of bubbles in the first place. There is a lot of speculation, and nobody can say for certain why, but there are theories. We already mentioned one: needing clean oxygen and water to protect fry. The other reason is that betta fry need to be close to the surface of water since they need time for their swim bladders to develop. Again, this hasn’t been proven.
The third and final theory is that proximity to the surface makes it easier for the fry to get nourishment. A number of microscopic organisms dwell on the surface of water. These organisms get trapped in the bubble nest and become food for the fry waiting inside.
How Often Do Betta Fish Build Bubble Nests?
Now that you know why betta bubble nests are constructed by male betta fish, you might have a question of when it happens. You might think that betta fish have a mating season like many other creatures, resulting in a predictable schedule of nest building and deconstruction. However, when it comes to the instinctual building of a betta bubble nest, it is difficult to say just how often it will happen.
First things first, there is no mating season. Female betta fish can produce eggs throughout the year.
Male betta fish will blow bubbles once in a while solely due to a natural inclination. All creatures have instincts to do something, such as pass on their DNA. For betta fish, the first step to doing that is to build a nest.
Yet, it is impossible to know when. Seeing one is indeed a good sign that your fish is healthy and happy. But just because a betta is happy doesn’t mean it will automatically start blowing bubbles. Additionally, there is no set standard for a bubble nest. No ideal time frame for construction. No standard size. Every betta fish is unique in how they blow bubbles for their nest, which is actually pretty cool when you think about it.
Some betta fish will produce nests weekly or monthly. Some might build a nest in a few days while others will spend weeks on their project. Sometimes, the nest will be just a few big bubbles. Other times, you might see a wall of tiny bubbles that is several centimeters thick. Maybe the nest will fill the entire corner of the tank.
But to say when this will happen? You can only cross your fingers and make your fish as comfortable as possible.
Do Betta Bubble Nests Occur Only When The Fish Are Happy?
Another common myth in the fish keeping community is that a betta fish will only build a bubble nest if it is happy. There is definitely some truth to that statement, but it’s not 100 percent accurate either. Happiness isn’t a qualifier for an instinctual display. Since betta bubble nests are something these fish are inclined to create, they don’t always need to be happy in order to do it.
There have been stories about bettas kept in dark, unclean tanks building massive bubble nests. Some betta fish displaying signs of illness will construct a nest. Meanwhile, perfectly happy male bettas may never build a nest. In other words, happiness is not a sole indicator of whether your fish will display this behavior or not.
How To Make a Male Betta Build a Bubble Nest
Although you cannot force your betta into building a nest, you can encourage males by meeting specific needs. Here are some steps to follow:
Keep the fish tank between 70-80 degrees F (21-26 degrees C). If your male betta is not comfortable, he will become lethargic and will not want to build a bubble nest.
Provide your male betta with at least one plant. The plant should be large enough to touch the surface of the water. In the wild, bettas use plants to hold their nests in place. Of course the more floating debris you have, the better.
Lower the setting on the tank filter. Optionally, you can create a filter baffle by putting an aquarium sponge in the outflow to slow down the flow. Bettas like calm water. Any surface movement may discourage them from building a bubble nest.
Maintain the parameters of the tank. Test regularly for spikes in ammonia, nitrate, and nitrite weekly. You should also change 10-15 percent of the water weekly. Keep in mind that if the betta’s tank is more than 5 gallons, you will need to change ½ of the water volume weekly.
Place a mirror beside the betta’s bowl or tank for about 5 minutes every single day. The betta will see his reflection and think that there is another male in the area. This could potentially trigger territorial displays, such as showing off to females, which the male betta does by building a bubble nest.
Similarly, you can add a female betta fish. This may be even stronger motivation for a male to start constructing a nest, because seeing a female will jump-start the instinct to breed. While it is unwise to add a female betta fish to the same tank as the male, you can add a divider to the fish tank or keep the two fish in separate bowls.
Of course, this can go one of two ways: helping or hurting your chances. Remember, they are also called “Siamese fighting fish” for a reason. You don’t want to keep betta fish within close proximity for long, because they can get stressed out.
Do Female Bettas Build Bubble Nests?
When you start doing research on betta bubble nests, you will find that only males typically build the nests. However, there is some evidence—mostly anecdotal—that mentions females making bubble nests as well. That said, you would need to investigate every single story individually to understand why it happened or how.
Sometimes, people confuse male and female bettas; so they might think their female is building a nest, when in reality, it’s a male. It’s also easy for a new betta owner to mistake a collection of bubbles on the surface of the water as a betta bubble nest.
But is the possibility there? Absolutely.
Betta bubble nests are just another unique aspect of keeping a Siamese fighting fish. Although bubble nests are not necessary, they are exciting. Watching your betta fish construct a nest of bubbles is bound to keep you entertained. And remember, it is also a sign that your betta fish is happy and healthy.
Do you have suggestions for promoting bubble nest building? Have any stories about female bettas constructing bubble nests? Leave a comment!