How Big Do Betta Fish Get (When They Grow to Full Size)

Last Updated: July 11, 2022 by Flora Gibbins

Betta fish are among the most popular household pets, courtesy of their robust personality and aesthetically pleasing demeanor. The ones we keep at home are likely from the Betta splendens species since they are the most common ones in stores.

So, just how big do betta fish get? 

Most stores sell them between 6 and 12 months. By this time, they are almost the size of a full grown betta fish of 2.25cm. You’ll also be smitten by their fully developed beautiful long finnage, making them appear even larger.

How Big Do Bettas Get?

Under controlled conditions, they may get to 3 inches. Some of the factors that may catapult their growth include the type of food, genes, water conditions, and general health.

The Betta anabantoids, also known as the giant betta, are peculiar among the betta fish species because they generally grow larger than the rest. While regular betta fish caps at 3 inches, this species can hit seven inches.

If you’re wondering which of these two species you should take home, here is my take. For a hobby aquarist who just wants a low-maintenance pet in the house, go for betta splendens. If you’re an enthusiast who loves taking things to the next level, the giant betta will appeal to your personality more. You’ll, however, need to feed them more frequently and get a bigger tank.

How Big Are the Fry/Baby Betta Fish?

Betta fish are bred from eggs. The incubation period takes 36 hours maximum. In 4-5 days, they begin streaming out of the nest.

The baby bettas are a little short of a ¼ of an inch at this stage. When you walk into a pet store to get your fish, it could be anywhere between 4-12 months. At that age, they are considered full-grown betta fish.

How Big Can Betta Fish Get?

As we had covered earlier, full grown ones seldom go beyond 2.25 inches.

It’s also imperative to note that the sizes differ between the male and female bettas. The disparity occurs because males have larger and longer fins than their female counterparts. Otherwise, their average length is generally the same.

Their cap on size is convenient for any aquarium enthusiast who fancies rearing betta fish. You’re assured of zero inconveniences resulting from them growing bigger, hence needing more space.

As a betta fish keeper, I’ll tell you that the size advantage and ease of care are perfect, especially if you’re a beginner.

Do Betta Fish Grow Bigger?

While there’s a cap to their size, there’s so much you can do to ensure it grows into its full size and live a quality life. Remember, once you take it home, its safety, health, and longevity become your sole responsibility.

For starters, get the right size fish tank. A five-gallon aquarium will do just fine for one betta fish. You also need to encourage their curiosity and intelligence by adding plants, ornaments, or any paraphernalia that keeps them engaged.

Proper feeding is non-negotiable. Betta fish are carnivores, and a good chunk of their food should be protein-based. I’m talking about feeds like brine shrimp, flakes, and bloodworms.

Be careful not to overfeed your pet. Remove any leftover food from the aquarium after five minutes.

Most importantly, you want to limit all forms of stressors from your pet. Betta fish are generally hardy, but they are still susceptible to common aquatic diseases. The water quality must be immaculately clean (this is where filters come in). And remember, betta fish are tropical freshwater fish, so the tank temperatures should be 76 to 82 degrees Fahrenheit.

Do Betta Fish Grow Depending on the Size Of The Tank?

This is one very controversial topic. While it’s true that the aquarium size can affect the fish size, this assumption is one-directional. If the tank is too small for the fish, its growth will be involuntarily retarded before reaching its full-size potential.

When the tank is larger, the fish will grow to its maximum size. Some can record a tinge of growth higher than their average size. The change is always 0.25 inches at most. We, however, can’t entirely attribute that to the size of the tank. You’ll have known other factors that improve betta fish growth by the end of this read.

Fun Fact: This would come as a surprise to most of you, betta enthusiasts! Did you know that bettas could live in vase aquariums? You read that right. Proceed to our article on Betta Fish Vase: Setup Guide And Maintenance Tips for interesting information!

Frequently Asked Questions

How big can betta fish get in different environments? (Comparing the size of wild betta fish against domesticated ones)

The betta fish in the wild stagnate once they get to their average size, 2.25 inches. The tamed ones have a better growth potential than those in the wild.

The discrepancy is mainly dependent on growth conditions. In the aquariums, they are safe, consume nutritious foods, and live in maintained water conditions.

Does deteriorating fins signal old age? Does that affect the betta size?

Should you notice spoiled fins, that’s a direct sign of rotting, and it’s not age-related. To fix this, clean the tank and remove any rough-edged or sharp objects like rocks if you placed some in the tank.

The sharp objects could be tearing the fins, which will impact their overall health. There may be no direct impact on its size, but injuries and discomfort may cause appetite loss, resulting in weight loss.

How big should my betta fish grow before they can breed?

The best time for betta fish to breed should be between 6 to 18 months. Having them reproduce under or above that period isn’t the most ideal. They are usually between 2 and 3 inches long within this time, which is about the size of a fully grown betta fish.

If you want your betta fish to breed, get an expert opinion.

Final Word

How big do betta fish grow? The average betta fish doesn’t grow so big. Finding one that is 3 inches is a stretch. It would be best to concentrate on treating them right, and you’ll have a happy, healthy, and vibrant little friend for years.

Also, originally, betta fish weren’t the glamorous slender-bodied, and vibrantly colored divas we see today. A lot of science of genome sequencing and selective breeding is responsible for their appearances. With these genetic improvements, you’re assured that your betta fish has the potential of living its life to the maximum.