Spawning your betta fish is a very exciting part of keeping bettas. Bettas lay eggs and spawn on a very unique and interesting way. Getting a succesful spawn is the beginning of your betta breeding adventure, so a good preparation pays off. 

If you’re planning on spawning your betta fish, you might wonder how to know when your spawn is successful, what betta fish eggs look like or how many eggs your bettas lay.

What do Betta fish eggs look like?

Betta fish eggs are small 1mm big and white balls. The eggs are not all fully round, but an oval unequal form. Eggs of mouthbrooding betta fish are bigger, around 2-3mm big and take longer to hatch. During the development of the eggs, they will swallow a little and turn more yellow.

Betta fish eggs hatching time

The hatching time of the eggs depends on numerous factors. On average, it takes around 2-3 days for eggs to hatch. The eggs of mouthbrooder bettas take much longer, up to a month.  

After this, the fry will start eating from their yolk sack and are still completely dependent on the care of their father. The fry can’t swim, and when they fall out of the nest the father picks them up and places them back in. After another 2-3 days the fry can swim and becom independant.

How fast precisily your eggs hatch depends on various factors, such as:


Because the eggs develop fully in the water, they are dependent on the environment they develop in to hatch properly. Because the metabolism is higher and digestion goes faster in higher temperatures, it has a big effect on how fast your eggs will hatch. Eggs in a 75°F+ environment can hatch in 24 hours, while eggs in colder temperatures can take more than 3 days to hatch. 

In a recent study about the link between water temperature and the hatching rate of eggs of Channa striata, the results were pretty clear. The higher the temperature went, the faster the hatching process went. It also had a big impact on the survival and hatching rate of the fry and eggs. Although the eggs hatched faster at 30-34°C, the hatch and normality rate declined. Around 28°C seemed to be the sweet spot, with highest factors. 

Altough Channa fish aren’t betta fish, this study insinuates the effect of temperature on betta fish eggs, who are actually similar to Channa in terms of habitat and genetics.

I find the best temperature for betta fish breeding and raiding is in between 26(79)  and 28(82°F) °C. This way you have fast growth and a high survival rate. It isn’t recommended to keep your adult bettas at this temperature, because they die faster in warmer water.

Water quality

It is pretty obvious that the water quality has a drastic effect on how fast your betta eggs hatch, and a drastic effect on the hatch rate. A bad water quality could result in a part of your eggs or fry dying off fast, or in extreme cases they could all die.

If your water has too much natural waste produced by poop of the fish / bacteria if your biological balance isn’t right, ammonia levels will rise, which are very harmful to fish. Apart from ammonia there are various other harmful substances and metals. If your tank isn’t clean enough, or you didn’t cycle your tank, these may damage your vulnerable eggs and fry.

Luckily, the chance your tank builds up harmful amounts of any chemical is pretty small and if you use the water in other tanks successfully you shouldn’t worry about this too much.

Make sure to always do a water change before spawning, put some catappa leaves and maybe a sponge filter in your tank. This way the risk of harmful chemicals being released is reduced.


Different Betta species have different hatching times for the eggs. Bubble-nesting betta fish eggs hatch very fast compared to other mouthbrooding species. For some betta species such as Betta macrostoma eggs can take longer than a month to hatch and free-swim! The average time for most mouthbrooding species is around 10-14 days.

How to know if betta fish eggs are fertilized

If your egg is slightly growing and showing gray spots, you can be certain the egg is fertile. Close to hatching you could also see a small fish in the egg, with a white yolk sack.

Spawning your bettas isn’t a guarantee that you will get fry out of it. Sometimes the male or female are not fertile, or your pair just isn’t experienced enough, which will result in a part of the eggs not being fertile. It is rare that all eggs in a spawn are fertilized and in some cases no eggs are fertilized at all. This is most likely a sign that one or both of the parents are infertile.

The male will eat infertile or damages eggs and only care for fertile fry. In some cases, inexperienced males can eat all eggs which is normal. By giving your male enough rest in a secure environment, the chance to a stressed male and the male eating the fry/eggs decreases. 

How many eggs do betta fish lay?

The average amount of eggs betta fish have per batch is between 30 and 100 eggs, but females can lay up to 400 eggs in a batch. Mouthbrooding bettas lay way less eggs, mostly between 10 and 20 a batch, since the male hatches them in his mouth.

The amount of eggs your female betta lays depends on several factors:

  • The size/age of the female

Betta fish sexually mature at an age of 2-3 months, but I advise against breeding at such a young age. It takes a lot of energy and is more risky for a small female to spawn. The best is to wait until your female is full grown and around the same size of the male, although she will usually be somewhat smaller. 

If the female is too big for the male, he can have a hard time clamping around the female when spawning and pushing the eggs out and fertilizing them. 

Small females will lay way less eggs than big and older females, because they don’t have the capacity to carry and make all the eggs and need to invest energy in growth. I find the age females are most productive is around one year old. Age is secondary to the size, if your 3 month old female already is full-grown it is safer and more healthy. The same applies to older females that are smaller. 

I find the best age to spawn is around 8 months to a year. My females are full-grown at an age of around 6 months, so this is the perfect time to spawn. At this age you know the full grown size of your betta female and that she matured enough to produce healthy eggs and can handle the male.

Females stay fertile for their whole life, but when they become older above 2-3 years, they will start becoming less fertile and producing less eggs.

  • Conditioning of the female

One of the most common reasons for small spawns is that the female isn’t conditioned enough before spawning. During the conditioning of your betta pair, the pair creates a will to spawn, and the female will start producing lots of eggs. The better you condition your pair, the higher chance of success will be, and the more eggs a pair can produce. 

If you have conditioned for more than two weeks, you can try spawning the pair. Never try spawning a pair without conditioning at all, since the pair has to be prepared for spawning. You can experiment with how much conditioning you give, since I don’t think everyone is waiting for hundreds of bettas hatching.

Conditioning can be done by feeding the pair multiple times a day with high protein live and frozen foods. Regularly show the pair to each other to encourage breeding behaviour and egg production.

Although bettas can lay a lot of eggs, it is rare that hundreds of eggs will hatch and become healthy fry. If the spawn is big, the male will usually eat a part of them, to make sure he can provide the best care to the rest of the fry. If your male is not so experienced, there’s a good chance a lot will be unfertilized, which he will eat.

However it is no guarantee that you will have bigger spawns or a 100% success rate, the chance increases vastly.

  • Experience of the female

More experienced females ‘know the drill’ of spawning and if you have a female that has spawned multiple times it’s likely that she will produce more eggs. When both your male and female are experienced, there is a bigger chance to more fertilized eggs and a higher survival rate of the eggs and new-bourn fry.

Betta fish spawning

Why do betta fish make bubble nests?

Bettas make bubble nests as a part of their breeding behaviour. The male builds the nest to provide a safe environment for the eggs and fry. When the pair spawns, the male places the eggs in the bubbles and will care for the newly-hatched fry and the eggs. 

In the wild bettas live in often oxygen arm and shallow pools. The small bubbles provide a steady environment with enough oxygen at the water surface to protect the fry in the most vulnerable days of their lives. It provides a hold-one for the small fry which can not swim yet.

Betta fish breathe using their labyrinth organ, which they also use to build bubble nests. The males will blow used air to the surface. Their favorite spots are covered in plants or leaves. Building a nest under a leaf or branch provides extra cover and less risk for the nest to be destroyed. 

Mouthbrooding betta fish

Although many people only know the Betta splendens, there are tons of other betta species around too, which are not all the same in terms of breeding behaviour. 

Not all circumstances allow betta fish to create bubble nests. Bubble nests are very fragile and are only suitable for shallow pools with no current and lots of natural cover at the surface. This is why species such as Betta macrostoma or Betta channoides don’t create bubble nests, but will use their mouth to hatch fry.

Mouthbrooding bettas mostly live in Indonesia, on the island of Borneo, Sumatra and Java. These habitats are different from those of bubble-nesters and are streams / pools that usually have some form of current in them and have less cover at the surface.

This makes building bubble nests not possible, so they have developed a way hatching the eggs in their mouth.

If you compare their mouth to the mouth of a bubble-nester, you can clearly see that they have bigger jaws and bigger mouths. This is because the male needs to hold the eggs and fry in his mouth for multiple weeks before hatching. 

Hatching the eggs in their gives them some serious benefits such as:

  • The male is able to guard the offspring all time and can get away without leaving the eggs /fry. Bubble-nesters can never leave their nest.
  • The eggs are in a more protected environment, and experience good cover in the male’s mouth.
  • There’s always enough oxygen flowing through the gills and mouth which is beneficial for the development of the eggs and fry.

But there are some disadvantages for mouth-brooders too:

  • The male can’t eat when caring for the fry
  • The male is more vulnerable for predators since he carries a serious burden with the offspring in his mouth.
  • They can have less eggs since the limited room in the mouth
  • The eggs hatch slower since they are bigger.

Betta fish eggs vs. other fish eggs

Sometimes, betta fish eggs can be confused with other types of aquarium fish eggs. Think about snail eggs, Corydoras eggs, or tetra eggs.

However, if you think about it, there’s one simple rule to know whether you see betta eggs or not: bettas always lay their eggs in a bubble nest.

So, if you see eggs laying in the tank or against the glass, it’s not the work of your betta pair.

Final thoughts

Thinking about breeding your betta fish? Getting the eggs is a very exciting part of your breeding journey. If your betta fish spawned succesfully, you will see small white balls in the nest of the male. But keep in mind that your betta pair can produce over 400 babies, so be prepared to raise up a lot of fry! The fertilized eggs will hatch after a few days and the fry will hang around a couple of days before spawning. 

Mouthbrooders are different and have bigger eggs, that hatch slower. If you aren’t prepared for hundreds of babies, wild betta moutbrooding species  are a better choice and will have less than 20 babies usually.