Betta Fish Growth Chart- Learn About Growth, Size,& Health

Whenever I feel confused that my bettas are well or not, I try to focus on the growth chart of the bettas that I got from one of my veterinarian friends.

As you know, betta fish don’t need excessive amounts of food or other materials. But they need enough caring which consists of some factors and those points determine the betta fish growth. 

That’s why I always suggest hobbyists make sure that they are providing enough care for the betta and that the fish is also going according to the growth chart.

Betta Fish Growth Chart

A betta fish growth chart is important if you want to know that your bettas are getting a healthy environment and they are out of stress.

If I want to mention only their length, I have pointed out their growth rate in the below table. You can check the growth rate from this portion.

WeeksGrowth (Inches)
1 day0.1 (Tail is not available)
1 week0.2
2 weeks0.25
3 weeks 0.34
4 weeks0.45
5 weeks0.6
6 weeks0.85 (Largest species grow over 1 inch within this time)
7 weeks1.1
8 weeks1.3
9 weeks1.55
10 weeks1.7
11 weeks1.9

Along with growing the size, the betta improves their body color and prepares for reproductive activities within 7 months. At that point, you can find it as a well-grown betta fish.

But in the journey of the achievement of this size, you have to go through several steps to keep your bettas undisturbed. That’s why go through the steps that I have mentioned in the following topics.

How Big Do Betta Fish Get? 

Betta fish can grow almost 3 inches long. However, this measurement varies from species to species. Some species don’t get more than 2 inches despite much caring.

Nevertheless, the caring issue determines the size of the betta fish. A healthy fish can grow faster and get a longer size than a stressed one. 

That’s why the size of the betta fish depends on the combination of different types of factors. But, the most supreme size of a healthy adult and long betta fish species is 3 inches.

How Fast Do Betta Fish Grow?

Beta fish have a moderate growth rate. It takes around 7 months to get raised from a baby fry to an adult one. 

But this growth rate is not fixed. Bettas can grow fast when they get their favorable environment and all their requirements at a specific proportion. 

Contradictory to that, if you can’t provide enough facilities for your bettas, they will grow at a slow rate and you won’t be able to get their perfect height always.

6 Ways to Tell the Age of a Betta Fish

1. Size

If you want to identify the age of betta fish, the first measurement can be their size. Compare the mentioned size of the betta fish that you want to determine from the chart.

It may be difficult for you as you can’t always take it out and measure it with scale. That’s w hy wait for some moments until it comes too close to you.

When it comes near to you, simply adjust the scale with the aquarium wall and try to measure the size of the betta fish. Then, compare it with the growth chart. You will get an idea about its age.

2. Fins

Sometimes, measuring with a scale gets too tough to identify their age. In that case, try to look at their fins. The aged betta fish possess longer fins than the young betta fish.

If you find that the fins are short and not so well developed, then it is a young fish. On the other hand, if you find that the fins are long enough, understand it as a mature one.

3. Lethargy 

Lethargy means the inactivity of the betta fish. The aged betta fish remain calm and don’t exhibit an excessive willingness to swim being quiet.

They take food and rest on the substrates inside the aquarium. On the other hand, the young betta fish are withal and roam inside the aquarium. 

Sometimes, they are seen dancing with their fins. If you find such characteristics in your betta fish, understand them as young. Otherwise, they are old or mature if you find them in a lethargic condition. 

However sometimes, diseased betta fish may also show lethargy though they are not mature enough. Hence, you can’t tell the age of a betta fish only depending on one character. 

4. Stripes

The next one is about stripes present in the body of the betta fish. If you notice your betta fish, you will find that there are some stripes on their body if they are in their young stage.

These stripes indicate that the fish haven’t developed their color fully. That means they are not mature yet. 

Again, mature betta fish don’t produce such stripes rather show plain and smooth color. 

But sometimes, diseased fish may exhibit such stripes too. That’s why don’t depend upon it only.

5. Eyes

Betta fish eyes are one of the most important indicators for their identification. Most of the aged betta fish have weak eyesight due to their disease infestation. 

If you notice carefully, you will see that their eyes have a streak-like appearance. If you can see such streaks, be sure that the fish is more than 1.5 years old.

But the young betta fish have no lines in their eyes. The younger fish don’t get attacked by the diseases always and that’s why we can see clear eyes on them.

6. Back

Lastly, let me mention one more point. You should check the fish while they are in the resting phase. The mature fish show a curve back while they are fixed or lying on the substrate. 

On the contrary, the young fish have almost straight back without any curvature. Thus, you can point out the age of a betta fish by following all these points.

Factors Affecting Betta Fish Growth Chart


Several factors determine the size of the betta fish. Among them, food is one of the mandatory issues. 

The size depends largely on the amount of food you are providing to them and the frequency of food provided. It also depends on the types of food that you have prepared for them.

If you take nutritious pellets for them containing mosquito larvae, bloodworm and mashed shrimps, it provides much nutrition to them and you should give two times feeding in a day.

Also, you know how important it is to provide enough nutrient materials to them. Hence, ensure that they are getting enough calcium, nitrogen, phosphorus, potassium and vitamin materials from their food habit.

Nutritious food with correct frequency helps them to circulate their mechanism properly and so they become larger.

2. Tank Size

Next, let’s talk about the tank size. If you keep your betta fish in a small tank, it doesn’t get enough space to swim and exercise. 

As a result, they remain inactive and don’t move their fins or body parts. On the other hand, if they get a large tank, they get enough space to explore themselves. Thus, they get a perfect growth period.

3. Sleep

Betta fish also need to sleep like human beings. Not only that, enough sleep at night is mandatory for their health and growth.

From this concern, you have to ensure that their sleeping is undisturbed and they are getting enough period to sleep.

It will help them to get sound health and thus you can get a healthy betta fish having the perfect growth period.

4. Gene Factors

In most of the cases, gene factors also determine the size of the betta fish. For example, the betta fish which is grown in a small tank, will produce dwarf bettas when they will breed. 

The vice-versa event will also happen in the case of larger bettas. You can compare this with the tallness and shortness of the human being.

Hence, if any betta is short due to its genetic factor, you can’t make it of the largest size despite being all types of caring. 

5. Water Quality 

The last point is about their water quality. The better their water quality, the more improvement will happen to them.

For example, bettas like pH range between 6.5 and 7.0. Also, the other elements available in the water like nitrogen, calcium, phosphorus, potassium and other minerals should be of optimum range.

If you can provide them properly, the bettas will grow faster. Along with maintaining them, you should also change the water regularly. 

Otherwise, the water will get toxic for them as different waste materials get mixed with the aquarium water. This factor is one of the most important matters for them.

How to Identify Adult Betta Fish?

If you can tell how to identify the age of a betta fish, then identifying an adult betta fish is easy for you. Maybe you already know the characteristics which are to be clicked.

Still, I am gathering those points together so that you can clear your confusion, if any.

  • They are almost 1.3 inches long or more than that. This size may vary from species to species. 
  • Adult betta fish show lethargic condition. Most of the time, they remain still and quiet inside the aquarium. 
  • They have a well-developed smooth color in their body. You won’t find any stripes in there.
  • As I mentioned above, they may have white streaks in their eyes due to disease infection. But don’t worry, a betta fish with low eyesight can live for many days.
  • They have larger fins which you can notice clearly while resting or swimming. 
  • Check their back portion. If it is found curved while resting, then it is a mature betta fish.

Thus, you can identify an adult betta fish easily by observing all these points.

How to Increase the Size of Betta Fish?

To increase the size of the betta fish, you have to provide enough care for them. Intensive care can make the betta fish remain free from any disease.

Also, their body mechanism responds fast and thus they start to increase fast. Hence try to maintain the below-mentioned steps to increase their size-

  • Keep them in a larger tank which is of at least 5 gallons. Bettas living in a small tank can’t grow more than 2 inches.
  • Provide nutritious food for them like pellets containing bloodworms, vitamins and mashed shrimp. Also, feed them twice a day and provide only that amount of food which they can consume within a few minutes. 
  • Don’t overfeed a betta fish.
  • Keep the water quality clean so that all the parameters are perfect for them.
  • Maintain the water temperature between 72 to 80 degrees Fahrenheit. 
  • Bettas release a hormone that is antagonistic to their growth. That’s why I change around 50% of the water regularly.
  • Try to provide 1 teaspoon of aquarium salt to 5 gallons of water so that they can remain free from pathogens. 

Thus, you can increase the size of a betta fish to its maximum size.

Can Overfeeding Betta Increase the Size?

No, overfeeding betta fish won’t help to increase their size. As I mentioned earlier, betta fish need a moderate amount of food and you have to provide that.

Providing excessive food won’t benefit them rather may create disease infestation and obstacles in their normal life cycle. 

For example, blotting and fatty liver disease are the most common and disastrous for them. Due to the disease attack, they show lethargy and become inactive. 


How long can a betta fish live?

A betta fish can live almost 2-5 years. If you provide enough food, proper tank condition and intensive care, they may live nearly 5 years without any issues.

Why is my betta fish getting slower?

It can be due to their age. If it is a mature betta fish, it can become slow due to their lethargy. But if it’s a young betta fish, inactivity can happen due to a disease attack or other types of stress.

How long does a betta fish take to grow fully?

Bettas take almost 7-8 months to get a mature size. In that phase, you can consider them as fully grown and after sometimes they will be ready for breeding.

Final Words

However, it’s a long discussion I have had with you about betta fish. Betta fish are preferable to most hobbyists due to their beautiful color and active movement. 

Simply, you won’t take adult betta in your fish that will show lethargy or remain inactive. Or, you may also bring them for breeding purposes.

In this case, you can easily try that chart to identify the age of the fish that you want. Also, a growth chart will help you to understand if the fish are having any problems or not.

Hence try to maintain the growth chart to provide a healthy life for your betta fish and to provide a vibrant color to your aquarium. 

Howard Parker

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