Bubble Nests

You may have noticed when looking at male bettas in the fish store that there is a cluster of tiny bubbles around the rim of their container. You may have even seen your own betta methodically blowing bubbles in your home aquarium. Well this isn’t because your betta is sick or bored. Your betta is doing what he does best. He’s preparing to care for his young.



Several betta species are bubble nest builders including the most common, Betta splendens species. In nature the males build the nest by clustering small bubbles on the surface of the water or under leafs or debris. When their nest is ready they coax a female underneath where they spawn. The females release the eggs, which are quickly collected by the males. The females do not participate in the protection of the eggs or the rearing of fry. Instead it is left entirely to the male who will closely guard the nest, warding off predators and collecting any eggs that may fall and returning them to the nest. After a few days the eggs hatch and the young fry continue to utilize the shelter of the bubble nest until they are ready to go on their own.

This nest building behavior is instinctual for male bettas and it is not necessary to have a female present to observe your betta building his nest. Most males will blow bubbles but the rate and size of the nest seems to depend on the individual male and possible other factors like age, health and water parameters.

Some males will frequently blow bubbles and you may find new nests on a weekly or even daily basis. Others may only blow a few nests a year. Healthy males tend to blow nests more often so if you see one consider it a good sign that your betta is happy and healthy. (A good sign doesn’t mean you shouldn’t continue to monitor your water parameters closely. Keep up with those water changes!) On the other hand, a lack of bubble nests doesn’t necessarily mean that your betta isn’t healthy. As mentioned earlier, bettas don’t all build nests frequently. The slightest current in your tank can discourage bubble nests too. Many betta keepers opt to cycle a tank and keep a filter running to create a more stable and healthy environment but may see less nesting due to the filter current. If this is your situation you could try to add some floating plants, float a styrofoam cup cut in half (to build a nest under) or try an adjustable flow filter. Bubble nests are great to observe but aren’t a necessity unless you are trying to breed bettas so don’t worry if you don’t see one.

As Murphy’s Law would have it, males love to surprise their humans with a nest right on the morning of their water change. Upon finding such a gift, most of us procrastinate on cleaning the tank for fear it will upset the betta. Of course, this isn’t very good for our fish’s health so here are two good tips.

1. It’s ok to destroy a bubble nest. He’ll get over it and will build you a new one. Clean water is much more important. Ignore the barking and furious fin wag. You’re bigger then he is.

2. Still devastated? Ok, you can scoop out the nest with a plastic cup or spoon and set it aside while you change the water and then ever so gently replace the bubbles back in the new tank.

If you’d like to read more on bubble nests check out a short Q&A on my blog entitled Bubble Nests & Bettas.