How Fast do Betta Fish Grow?

If you’re the proud new owner of a betta fish or nine, you probably are very curious about their life stages, especially if you have a bunch of baby bettas swimming around or it’s your first time breeding bettas.

Betta normally grow up to 2 1/4” in length (the adult average length) and they can reach that point in as few as 12 weeks, although they are considered to be full-grown adults at about 7 months, so long as they are properly taken care of, fed, and have a lively, space-filled environment in which to thrive and grow. 

That’s not to say that they all grow to 2 ¼”, as some betta may grow larger and the runt of the litter may be a little smaller. Betta are known for reaching 3”, though it isn’t a common occurrence. For the most part, it will take around three months for them to reach the length of a fully grown adult, although they may grow more.

However, for betta to be healthy, thrive, and grow to their full length, they need a proper tank environment, as well as the conditions that are conducive to growth. There are a lot of factors that go into that, more of which we will cover below.

Purple and Red Betta

Betta Growth Stages

There are four stages that betta go through as they grow larger, the first stage representing nothing more than an egg.

Bubble Stage Eggs

When the male betta is ready to mate, it already instinctively assumes that it will be successful and begins preparing a bubble nest, which is composed of air and the betta’s saliva. It’s pretty much the same thing that you can do when you make spit bubbles.

This “bubble sack” is where the eggs will go when the female betta gives birth. This is the first stage of a betta’s lifecycle, nothing more than an egg suspended in its father’s spit juice.

Fry Stage

This is the stage immediately after the betta emerges from the eggs and it lasts up until roughly six weeks. Throughout this period of time, they are known as betta fry or just fry. At this point in time, the betta is extremely tiny, at 0.1” and they have no visible tail to speak of.

By the time they emerge from the Fry stage, they are roughly 0.75” in length, at which point they enter the third stage of the betta life cycle.

Juvenile Betta

The teenagers of the betta life cycle, also known as “Juvenile” betta. They are anywhere between 0.8” and 1.1” when they enter this stage. The moment that they leave their egg sack is largely dependent on what size the egg sack is.

The juvenile betta will not move to the next and final phase of their life until they are one year of age.

Adult Stage

At this stage, your betta will be anywhere between 2.25” and 3.0” long. They are considered adults now and they will already be halfway through their average life span. On average, betta only live for 2 years, however, they’ve been known to live for up to four years.

Do Betta Grow According to the Size of Their Tank?

While betta aren’t as inhibited by their environment as snakes and other reptiles, having too small of a tank for bettas to live in will stunt their growth over time. Of course, none of that touches on the psychological problems that too small of a living space can create with your betta and none of them are good things.

You have probably heard and even seen tiny tanks that house betta, some as small as one gallon. That’s a common misconception and you should not have your betta in such a confined manner.

The recommended tank size for betta fish is 5 gallons. Of course, if you are breeding betta or just own several more of them, you will want to have something a lot bigger. Ten gallons sounds like a lot but in terms of aquarium sizes, it really isn’t.

Can a Tank be too Big for a Betta?

You are free to go much larger as plenty of space is not going to harm a betta, so long as you can find things that will keep them entertained. You don’t just want a 15-gallon tank that is filled with nothing but water.

You’ll want lots of plants for them to explore and maybe some ornaments such as a giant shipwreck or something similar. Your betta will appreciate all of the exploration options that you provide for it. A happier betta fish is a betta fish that will live to the maximum extent of its life.

We stated above that the average lifespan for betta fish is 2 years, however, they have been known to live up to 4 years. If you want yours to push the limits, the happier it is, then the better the odds will be that your betta will meet and exceed 2 years of life.

That’s not to say that an underwater castle will make your betta live longer, only that it will improve your betta’s quality of life, which may help it live longer.

Final Thoughts

In general, a betta shoots through its juvenile stage and into a fully grown betta in about three months. Some take longer and some go through it quicker. There are also disagreements on what constitutes an “adult” betta. Regardless of whether or not it is considered to be an adult, it will grow quickly and max out around 2.25”.