Betta Fry Growth Stages: A Full Guide With Pictures

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Betta fry are pretty exciting creatures, especially in their early days. But they also raise many questions. How long does it take for them to grow? When are they sexually mature? What are their growth stages? Well, today, I will cover all of these questions in detail.

Here is a table summarizing the betta fry growth stages:

StageAgeSize (inches)
EggDays 0-3<0.10
NewbornDays 3-7~0.10
JuvenileWeeks 1-30.15-0.35
YoungMonths 1-30.35-1.40
AdultMonths 3-52.00-3.00

I will elaborate on the different betta fry growth stages and share some detailed pictures as we move forward. These will help you identify your current betta fry stage and what to expect in the upcoming weeks.

Still curious? Feel free to check my complete guide on betta fish fry, where I discussed how to care for betta fry, what they eat, their growth stages, what equipment to use, and much more.

What Are The Betta Fry Growth Stages?

If you want to buy your bettas from a fish store, avoid the young ones. They are more difficult to inspect because they haven’t developed all the physical attributes that matter to you. Aim for seven weeks or older. 

If you want to breed and raise young bettas in a home aquarium, you will observe the following physical and behavioral changes:

Stage 1: Egg (Days 0-3)

This is the starting point. The female makes the eggs and pushes them into the water for the male betta to fertilize. You cannot predict the duration of the breeding process. 

Mating can last hours or a few days, depending on the health of the breeding pair and the conditioning you did.

Some female bettas can refuse to release their eggs because of the poor conditions in the tank. But if mating occurs successfully, the male betta will keep the eggs in a bubble nest until they hatch.

You should notice the white cluster of eggs within 36 hours. If you take a closer look, you will also see the eyes and tails of the fry in the eggs as they develop.

The male betta may blow more bubbles to support the eggs, especially if they start falling from the nest. It generally takes up to 72 hours for the eggs to hatch.

Betta fry growing in their eggs – the eyes can be seen at this point.

Stage 2: Newborn (Days 3-7)

The betta fry will hatch within two to three days. Don’t expect every egg to hatch, as some eggs will probably go unfertilized. The exact number will depend on factors like the conditions in the tank and the age of the male betta.

Young males that have never mated before are more likely to do a poor job of fertilizing the eggs. The newborn fry will hang around the nest for 24 hours. Once the babies wander away from the nest, you can remove the male betta.

Let your observations guide you. Sometimes, it takes three or more days before the babies learn to swim horizontally. They will survive on the yolk sac during this period. 

The male betta should stay in the tank to protect them until they are strong enough to stray from the nest.

Newborn betta fry under 24 hours old, still hanging to their bubble nest.

Stage 3: Juvenile (Weeks 1-3)

Betta fry are classified as juveniles after they leave the nest. They remain in this stage for two to three weeks. The labyrinth organ will develop during this period, allowing the fish to extract oxygen from the air.

At this point, your betta fry become free swimmers and start swimming horizontally. In some cases, they will sink to the bottom of the tank, which is entirely okay.

Three weeks old juvenile betta fry that still didn’t get its colors.

Stage 4: Young (Months 1-3)

I usually recommend buying bettas from the fish store during this stage. Wait until they are seven or ten weeks old. You will get a better sense of the betta fish’s attributes, not just their colors but the dimensions of their fins.

Young betta fish cannot reproduce at this stage. Therefore, if your goal is to avoid mating, you don’t have to separate the male and female fish just yet. 

Although, some people don’t want to take any chances. They will place the bettas in separate tanks the moment the creatures manifest their fins and colors.

If you have grown your betta fry in a breeding tank, at this stage, it is the right time to separate them. At two months of age, the male ones start posing a threat to each other.

Two months old young betta fry, swimming freely in their tank.

Stage 5: Adult (Month 3 And Onwards)

Many fish stores will classify betta fish as adults at the age of 7 months because of their size.[1] However, for many aquarists, adulthood has nothing to do with the betta’s size.

Different bettas will grow at different rates. It can take some fish up to a year to reach their full length

Professional breeders prefer to associate adulthood with sexual maturity. With that in mind, you wouldn’t be wrong in calling a betta fish an adult at three to five months of age.

Fully grown male betta fish, building its bubble nest.

What Are The Betta Fry Size Changes?

Many aquarists do not differentiate between the various stages of a betta’s development. To these individuals, bettas are fry when they hatch, and after six weeks, they become adults, even though they are sexually immature. 

But even if you can’t tell when a fry transitions from the fry to juvenile stage, you can still record the following differences in the creature’s size during the first ten weeks:

  • 0.1 inches when they hatch.
  • 0.25 inches at two weeks.
  • 0.45 inches at four weeks.
  • 0.8 inches at six weeks.
  • 1.3 inches at eight weeks.
  • 1.5 inches at ten weeks.

Fully grown bettas have an average length of 2.5 inches. But some aquarists have raised 3-inch-long bettas. The male bettas look bigger, but only because they have larger fins.[2] 

What Are The Betta Fry Weight Changes?

A baby betta’s weight ranges between 0.02 and 0.05 grams. That figure will jump to 3 or even 4 grams as the fish develops.[3] But the final weight will depend on the creature’s diet. 

You will observe the following changes as the babies grow:

  • 0.01 to 0.02 grams when the fry hatch.
  • 0.03 grams at one week.
  • 0.05 grams at one month.
  • 2.5 grams at three months.
  • 3.0 grams at four months.
  • 3.5 grams at five months.
  • 4 grams at six months.

Do Betta Fry Eat Different Foods As They Grow?

You don’t have to feed the babies for the first 24 to 48 hours. The yolk sacs will provide all the nutrients they need. Wait until the babies can swim freely before feeding them.

  • They will eat infusoria and nematodes in week 1.[4] 
  • Introduce baby brine shrimp to the diet in week 2.
  • Experiment with larger foods like bloodworms in week 3 or 4.[5]
  • Add some variety to their meals, such as Grindal worms and Blackworms. You can introduce freeze-dried or frozen foods in week 5 or 6. 
  • The baby bettas can eat dry pellets at this stage. They can start eating the same foods the adult bettas enjoy by week 8 or 9.

For more information on what betta fry eat, check this article I wrote. I also embedded some helpful videos that will show you how to feed them properly.

At What Age Do Betta Fry Get Color?

Bettas are beautiful fish. Over the years, aquarists have used selective breeding to create bettas with incredibly vivid colors.[6] Therefore, it is not that difficult to understand why the colors matter to an aquarist.

You don’t want to ruin your aquarium by adding bettas with ugly colors. But betta fry are translucent at the start. You cannot judge their colors during those first few weeks.

You have to wait until week eight or nine for the creatures to show their colors. But even then, the colors may continue to change until the fourth or fifth month.

Don’t make assumptions about a betta’s appearance based on the colors you see in the first few weeks of the creature’s life.

How To Make Betta Fry Grow Faster

The first step here would be to feed the betta fry properly. Until their juvenile stage ends, you should feed your betta fry approximately five times a day.

Researchers found that baby fish exposed to a higher feeding frequency enjoy a higher survival rate.[7] Therefore, it is best to feed your betta fry in small quantities multiple times a day.

Follow the guide I linked earlier to see what betta fry should eat. You should generally stick to protein-rich food like infusoria and baby brine shrimp.

It is also worth mentioning that betta fry produce what is known as Growth Inhibiting Hormone (GIH). In other words, a hormone that makes them grow slower.

If you perform frequent water changes, you will remove this hormone. By doing so, you will indirectly make the fry grow faster. A fifty percent water change each week will suffice.

I also suggest that you stick to these water parameters:

  • Temperature: 85-88° F (29-31° C)
  • pH: 7.0-7.2
  • General hardness: 2-20 dGH (70-300 ppm)
  • Carbonate hardness: 3-5 dKH (55- 90 ppm)
  • Ammonia: 0 ppm
  • Nitrites: 0 ppm
  • Nitrates: <20 ppm

Keeping the water parameters within the desired range will keep your betta fry stress-free, and they will be healthier and more willing to eat.

To measure the pH, ammonia, nitrates, and nitrties, I personally use the API FRESHWATER MASTER TEST KIT (link to Amazon). It lasts for about eight hundred measures, making it highly cost-effective.

For the water hardness, you can simply go with the API GH & KH TEST KIT (link to Amazon), which is pretty cheap and easy to use.

If you found this article helpful, these may also interest you:

Pro tip: If your betta fish breed frequently, you probably need to know a little about their eggs. You can find my complete guide on that topic here.


Up until the 3rd week, betta fry are considered juvenile. At this point, they are no longer attached to their bubble nest. You will probably see them swimming horizontally across the tank, and that is when the male betta should be removed.

The fish are considered young bettas between the first month and the third. Towards the end of this stage, they reach sexual maturity. When this happens, some professionals consider them adults.