Betta Fish Growth Stages – From Fry to Adult

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Watching your betta fish grow and spawn from the eggs is an exciting process. It takes from a few weeks to a couple of months for the whole process to happen.

If you have never seen this process happen, or you are just interested in it, then you will learn about it here.

How does a betta fish go from an egg spawn to the mature betta fish? We will cover the whole process here, from the mating process to the mature betta fish.

1. Betta Eggs

The first stage of the process is obviously the mating process. This step is an interesting one to watch unfold; the male betta fish will build bubble nests covered with mucus, and then he will proceed to chase the female. He displays his vivid colors and fins to the female to attract her, which makes for a stunning sight.

Once he manages to catch her, the mating process is set to happen. The male wraps around the female and fertilizes eggs into her body. Shortly after, the 7 to 10 eggs spawn, which are then collected by the male. He takes these eggs into his nest, where he protects them.

2. Newly Hatched Betta Fry

After 24 to 48 hours, these eggs will hatch in the nest. It is not clear how many fry spawn – the number can be anywhere from 1 to 300.

Shortly after they spawn, this fry will stay around their eggs and feed on them for another 24 hours; they can stay in and around these nests for an additional couple of days.

Then, the fry is ready to leave and start moving on their own. This is when the male should be removed from the tank.

3. Juvenile Betta Fish

In the first couple of weeks, the juvenile betta fish will start developing their initial colors, which will not be as clear as they will be later in their life cycle.

In this stage, they will also develop their labyrinth organ, which allows the fish to breathe oxygen from the air.

At this stage, the bettas can reach the size of about an inch, but most probably, they will reach about 0.6 inches to an inch at most. This stage lasts about 2 to 3 weeks before the betta start growing up faster

4. Young Betta Fish

This stage is very important for their development. It is at this time that they start to develop their vivid colors, and their fins start growing. At this stage, as they start to mature, they are still not fertile and not able to reproduce yet.

At this stage, the fish are seven to ten weeks old, and the process of growing up can last to about three to four months. This is an important step to maturity, and they will be considered mature when they are able to reproduce.

5. Adult Betta Fish

The betta fish are considered adults when they reach sexual maturity. This is when the growing process is almost done; at this stage, they grow to about 2 inches or slightly more – to 3 inches at most.

You will know when the betta fish is considered an adult fish, as you will see major changes in their behavior towards other fish. The male’s behavior towards females will also change, as they will start to chase them to start reproducing.

The adult stage of the betta fish is the longest, as it lasts for 2 to 3 years, depending on how long the fish live. It starts when they are about 3-5 months old and continues for the rest of their lives.

When to Separate Betta Males from Females?

It is possible to keep male and female bettas together, but it can be a complex environment. You see, the females might feel intimidated by the male’s presence and might start hiding, and you might not get the best out of the female betta. This is why this can only be done by fish keepers who have experience and knowledge about this.

If you want to keep them together, you can. It is better to keep them in separate tanks, however, and you should separate them when they grow up.

At the adult stage, the male will pursue the female relentlessly, leaving little space for the female to thrive. This is why it is better to separate them and put them together if you want them to breed.

How Long Until Bettas are Fully Grown?

Even though the adult stage starts when they are at about 5 months, they can still continue to grow. Even after they mature, the bettas can grow half an inch or more, so the growing cycle only stops when they are about a year old.

That is when they are considered fully grown and are unlikely to grow even more. Generally, the largest amount of growth stops at about 3 to 5 months into the life cycle.

What is the Maximum Size for Betta Fish?

The size of the fish can vary; for example, some betta fish types have larger fins and are thus considered as larger; some fish might grow larger.

This is especially the case if you compare males and females – the males will grow significantly larger than females. In general, the betta fish can reach to about 2 inches in size, and 3 inches in rare cases.

Do Female Bettas Grow Faster than Male Bettas?

There is no big difference in the growth rates of males and females, but females do tend to grow slightly faster than males. But in the end, they reach smaller sizes than males – their sizes can differ to up to an inch.


The bettas are one of the most popular fish for breeding. They live about 2-3 years with good care and adequate tank conditions.

It is maintaining them properly and giving them good care that matters, whether they are female or male bettas.

Their life cycle is an interesting one, and we hope that you have learned a lot about the bettas here.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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