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How Big Can a Betta Fish Get? (Tips To Help Them Grow BIG)

Understanding the biology of our fish can be one of the most enjoyable parts of the fish keeping hobby. The more that we have the chance to learn about the denizens of our aquatic tanks, the more that we can better understand and take care of their needs.

Knowing just how large our betta fish grow can help us determine how large of a tank we may need, and help us set a realistic expectation for what our future with these beautiful fish can be.

If you’ve ever asked the question “How big can a betta fish get?” read on for the answer!

Betta Fish Background

Betta Fish Near Rocks
Betta Fish Near Rocks

Wild betta fish, or Betta splendens are a fascinating animal that has adapted to maximize their survival chances in an oftentimes hazardous environment.

These small creatures often seem especially suited to smaller tanks, but it is best to keep in mind that they still require plenty of room in order to feel safe.

Habitat

The natural habitat of the betta fish is the warm, tropical waters of Southeast Asia, specifically around the areas of Thailand, Cambodia, and Vietnam (hence the moniker siamese fighting fish).

These areas are prone to periods of drought, and as such this ingenious little fish has adapted a specialized tissue system known as the labyrinth organ.

These enable the fish to breathe surface air, meaning that they can survive for periods of up to 6-8 hours on dry land while hopping between shallow bodies of water.

How Big Do Betta Fish Get In The Wild?

Unlike species like the goldfish, which can reach incredible sizes of upwards of 18.7 inches in length, betta fish tend to stay on the smaller size, both captive and in the wild.

Wild betta fish are known to reach sizes of between 2.5 and 3 inches in length maximum. These small fish are better adapted to relatively small areas such as rice paddies and small ponds, places where a larger fish would surely begin to feel cramped for space.

Territorial

This does not mean that they do not need their proper amount of space, quite the contrary. Male bettas especially will vie for territory, putting on elaborate defensive displays and even fighting off other fish for an adequate amount of room.

How Big Can A Betta Fish Get?

The largest Betta I have ever seen and what I feed him

Generally speaking, betta fish are a relatively small breed, suited to a small tank of 3 gallons or more. It’s not uncommon to see your betta grow to the size of 2.5-3” in length over the course of its life, but one should not expect them to grow much larger than this.

How Big Can A Male Betta Fish Get?

Including the fins, male bettas get to an average length of 2.5-3” at their full size. Some bettas may be slightly smaller due to differences in diet or breeding, but they will tend to stop growing upon reaching this size.

Males usually have larger fins than a female betta, and come in more exciting, vibrant colors.

How Big Can A Female Betta Fish Get?

Male and female bettas reach the same size of 3 inches long at their maximum growth. Female betta fish will tend to have slightly smaller fins than the males, but this doesn’t mean that male bettas grow bigger.

Additionally, females tend to be more dull in appearance and color than their male counterparts, as they do not use display-based tactics to gain territory.

NOTE

For those interested in breeding, baby bettas begin at about 0.3 inches long as eggs, then will hatch and reach around 1.9 inches of growth over the first 11 weeks of life. After seven months, they’ll reach their adult size of 2-3 inches in length, and will cease to grow larger.

Do Betta Fish Grow To The Size Of Their Tank?

A common misconception about betta fish (and many other species such as goldfish, for that matter,) is that their growth is dependent upon the size of their tank.

As you may be able to tell based on the previous information, while minimum tank size is very important, bettas are limited in how much they can grow more by the genetic capacity that they have for growth than by the environment around them.

NOTE

Feeding your betta a balanced diet high in proteins and essential amino acids is the best way to help them grow, rather than simply buying a new tank. The food that your fish eat is an integral part of how healthy they are.

If betta fish were simply able to grow to the size of wherever they lived, we’d be hearing more stories of fully developed fish reaching enormous sizes in the tropics where they originate! Likewise, we’d see our fish never stop growing as we buy larger tanks over time.

How Large Of A Betta Tank Do I Need?

Blue Betta at the Bottom of an Aquarium
Blue Betta at the Bottom of an Aquarium

While some pet stores may try to sell you on the idea that your betta tank can be a tiny bowl of no more than 1 gallon, this is a surefire way to set them up for health complications and even premature death.

NOTE

You may have even seen pet store betta fish come in containers as tiny as small cups. This does not mean that this is enough space for these fish to thrive!

The reason for this is that in small tanks without much water flow or proper filtration, fish wastes, decaying matter and other toxins can quickly accumulate. This leads to a massive spike in the ammonia content of the tank, meaning that toxic shock can be imminent.

This causes your betta to have a reduced immune response, along with damaging their sensitive gills which can lead to death.

Minimum Tank Size

At a minimum, I recommend at least a 5 gallon tank for a single betta fish. When considering having multiple bettas or a community of other fish, a bigger tank is necessary to prevent nipped fins and constant battling.

My article “How Many Guppies In A 5-Gallon Tank?” might help you figure out what kind of tank size you need.

For a single male betta with peaceful neighbors such as mystery snails and plecos, a 5-10 gallon tank can work just fine. For a tank with a male and female, or one with a “sorority” of multiple females, consider a tank of between 10-15 gallons with lots of hiding places as a good starter. Check out this review of small fish tank stands, you might need it later.

What Is The Best Tank Size For Betta Fish?

Betta Near Aquarium Wall
Betta Near Aquarium Wall

For a single betta, a minimum of 5 gallons should be adequate. When looking to add a variety of species, or more than one betta fish, consider tanks of 10-15 gallons as a good starting place. 

Keep in mind that having multiple males will cause territorial disputes and fighting over food, leading to nipped fins and potentially even death for one of them.

Mixing a male with multiple females can work, and this setup allows the male to distribute his attention to more than one female, saving an individual from extra harassment.

Helping Your Betta Reach Its Maximum Potential

While there is no surefire way to ensure that your fish will grow to a certain length, there are some good practices when it comes to what we feed and how we set up our tanks that can keep them healthy and strong.

pH Level

A relatively neutral pH of 6.5-8 works best for bettas. They are a hardy fish and capable of handling levels outside of this range, but they thrive best in a more neutral environment.

Temperature

Bettas do best with a temperature between 75 and 80 degrees Fahrenheit.

Diet

Bettas are carnivores, and require a balanced diet full of vitamin and mineral-rich foods. Feeding them a mix of pellets/flakes that are specifically formulated for them, along with live foods and things like freeze dried bloodworms as a supplement can be a great way to vary their diet.

NOTE

When establishing a diet for the fish in your tank, I recommend consulting with a trained veterinarian or aquarist to ensure that all of their needs are properly met.

As a side note, if you decide to simply feed them more food this will not likely make them grow any faster. Overfeeding can lead to serious health complications such as bloat and stomach problems, so stick to your set betta feeding schedule for best results.

Conclusion

Throughout today’s article, we looked at how big can a betta fish get, both in the wild and in captivity, along with some helpful tips for getting them to reach their maximum size.

In general, bettas get to around 2.5-3” in length at full adulthood, and will stay the same size for the rest of their lives.

Providing clean water, adequate tank parameters, and a balanced diet are by far the best ways to maintain the overall health required for bettas to reach their largest potential size.

Feel Free To Share!

As always, thank you for taking the time to read today’s post on betta fish care. For another interesting read, find out if betta fish can see in the dark or this review about filters for small tanks.

Feel free to share this information with any other betta fish fanatics you may know, and I wish you the best of luck on your continued aquarium adventures!

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Mollie Newton
Mollie Newton
Founder of PetMeTwice. I love all types of animals from fish to fluff-balls! I also enjoy writing short stories and helping train animals 🤩