How Big Should a Betta Fish Tank Be – Best Size Options?

This article may contain affiliate links (disclosure policy).

Sharing is caring!

Amidst the excitement of bringing home these charming creatures, one crucial question often arises: what is the optimal tank size for a Betta fish? This comprehensive guide debunks common misconceptions and provides practical recommendations to help you create a comfortable and healthy environment for your beloved Betta. Join us as we unravel the secrets of Betta care, empowering you to make informed decisions and embark on a rewarding fishkeeping journey.

Siamese fighting fish
Siamese fighting fish

Nevertheless, I’ve noticed that, often, a new betta fish owner doesn’t know what tank size would be the best for keeping their small pet happy.

Is a 2-gallon aquarium a good enough setup, or is 5 gallons the bare minimum for one of these fish?

For starters, I can assure you that those 1-gallon bowls, frequently recommended at pet stores, won’t match the needs of any betta.

It may be true that your new fish will survive if you’re keeping it in, say, a 1-gallon aquarium with dimensions of 4 x 6 x 8 inches.

However, I shouldn’t need to remind you that barely surviving doesn’t mean thriving.

If you want to keep your betta happy and healthy for longer, you should aim to provide it with a more spacious tank.

Typically, a 3-gallon tank has the absolute minimum volume for housing Bettas, but a 5-gallon one is preferable and widely accepted as the norm.

But is there a maximum, and can a tank be too big for your pet?

What if it’s the “Giant” Betta variety?

Does it matter if it’s a female or a male?

Even if you’re setting up a sorority or a breeding aquarium for two, in this guide, I’ll show you how big a betta tank should be and why.

What is the Optimal Betta Fish Aquarium Size?

When it comes to ideal tank sizes for a betta, you should keep in mind that these curious fish love to explore their surroundings in their natural habitat. Furthermore, my experience has been that Siamese fighting fish need hideouts where they can retreat from time to time.

This means that apart from a substrate, your new aquarium setup also needs plants and driftwood or a cave ornament that will keep your betta’s stress levels as low as possible.

Decorations will take some of the fish tank’s capacity. So do the filter and heater that you must include to make the tank habitable for your Betta.

The optimal aquarium choice manifests itself in the balance between swimming and hiding spaces.

So here’s the ideal tank size for a Betta fish:

A 5-gallon tank (18.93 liters) is the optimal size for one adult betta fish to live a comfortable and healthy life. An aquarium capacity like that has enough space for swimming and some hideouts for a Siamese fighting fish. Your betta’s stress levels will remain low which may extend its lifespan.

I need to note that decorative male bettas have larger fins compared to females.

That being said, a 3-gallon tank is the bare minimum for a betta fish tank, whether it’s a male or a female specimen. Such small tanks can accommodate no more than 1 specimen and that’s somewhat pushing it.

If you currently have a tank that’s 1 or 2 gallons in volume, you’d want to upgrade it to a larger one (AT LEAST a 3-gallon one).

How Do Small Tanks Impact the Life of a Betta?

Betta Fish in small pet store container
Betta Fish in small pet store container

Fish tanks that are too small will result in a lower quality of life for your pet betta.

And that’s not only because of the lack of swimming space.

In tiny aquariums, the water gets polluted very quickly by the decomposition of fish waste.

This leads to frequent fluctuations in pH, ammonia, or nitrite levels in your new tank, which are all harmful to freshwater fish.

The unstable environment may lead to atypical behavior or may even have lethal effects on your aquatic pets. It’s much easier to maintain stable water parameters in larger fish tanks since there’s more room for error, especially if you’re a beginner.

Finally, small tanks are typically less oxygenated, and studies suggest this, alongside higher Nitrate levels, may impact the growth rate of a juvenile fish. To not stunt the growth of your pet Betta you’d want to go with an adequate tank size.

What is the Best Tank for a Regular Betta Fish?

What is the best betta fish tank size?
What is the best betta fish tank size?

If you must go small, I always recommend going for a 5-gallon aquarium to start with. I’ve even listed the Betta fish as one of the best species for a small tank like that.

Read for further research: The Best Betta Fish Tanks: Beginner’s Guide

The common saying “the bigger, the better” applies to its full extent when it comes to fish tank sizes. You CAN’T get an aquarium that’s too big for a Siamese fighting fish.

If you opt for a 20-gallon tank for just a single betta, your tiny fish will be more than happy to explore the corners of its new spacious home.

Just make sure there are enough hiding places such as plants and caves to make your pet feel cozy and safe.

How Big Should You Go for a Giant Betta?

When discussing how big the fish tank should be, we need to consider the type of betta you have and the number of fish you want to look after, in general.

A common betta can reach between 2.7 and 3 inches in length.

Giant Betta fish, however, grow to about 6 and sometimes even 7 inches.

Since the Giant betta breeds almost twice the size of a regular male you should ideally get a 10-gallon tank at the minimum for them.

Optimal Tank Size For Breeding Bettas: The Minimum Size for Two Bettas?

If you want to set up a breeding aquarium with two regular bettas – one male and one female, a 10-gallon tank is the minimum tank size.

Breeding bettas involves the installation of a divider, which separates the tank into two 5-gallon sections.

This space is sufficient to provide a healthy environment for both fish before mating.

What Are the Recommended Aquarium Sizes for a Female Betta Sorority?

If you’re not new to the hobby, you may also be tempted to start a betta sorority tank.

Unlike aggressive males, female betta fish can live together peacefully, as long as you provide them with the appropriate conditions.

Usually, hobbyists keep no more than 5 or 6 females in this type of setup.

20 gallons is the minimum tank size for a sorority of 5 female bettas.

Also, if you have the possibility – go for the 20-gallon “Long” because that will provide your fish with more swimming space. You can find the dimensions of all aquariums in this resource page.

Ideally, however, I would go with a 30 or a 40-gallon one for a Betta sorority.

Betta Care Tips and Tank Setup for Beginners

fully set betta fish tank
Fully set planted betta fish tank – Image by LouTheRescueBetta

Bettas are widely popular among beginners and also advanced aquarists. And that’s not only because they’re cool-looking fish, with attractive behavior. Aside from their beautiful coloration, novice aquarists are drawn to Siamese fighters, because these small creatures are often described as one of the hardiest fish species as they are relatively easy to take care of.

Indeed, betta fish can survive severe conditions, including small fish tanks that are low on oxygen.

After all, these fish can use their “labyrinth” lungs to breathe atmospheric air from the water surface. Nevertheless, this doesn’t mean that you should neglect their requirements or take minimal care of them.

Opting for the ideal tank size that provides enough swimming space isn’t enough.

To be happy, a betta would also need its private space, which often comes in the form of live densely planted aquatic plants.

Betta fish come from the rice paddies in Asia, where there’s plenty of aquatic vegetation.

Having a decently planted tank helps your fish to feel more at home, which in turn will help it become more confident. Luckily, there are many beginner-friendly plants such as Java Moss or Java Fern.

Furthermore, you can find a nice piece of driftwood yourself. It too will serve a decorative purpose and take your tank’s looks to the next level.

Author’s Note: Male Betta fish tend to get quite territorial and aggressive towards their tank mates. Therefore, I’d recommend keeping yours alone if you’re new to the hobby.

Still, you can check out my bulletproof list of possible tank mates if you’re determined to set a community aquarium with a Betta fish as the centerpiece. Bear in mind that 10 and 20 gallons are the best aquarium sizes if you are to keep your betta fish with some of its compatible tank mates. Not many of the fish that can coexist with a Betta in a 5-gallon aquarium are beginner-friendly.

With that being said, you should know that keeping two male Siamese fighting fish in one aquarium is virtually impossible, no matter the size of the tank. Since males are more territorial and aggressive, they tend to attack each other, which often leads to fish deaths.

Anyway, when it comes to the aquarium’s setup, here is the gear that I recommend for one betta fish in a 5-gallon tank:

  • A properly-sized heater is needed to keep the water temperature stable within the optimal range for a betta (75 °F to 82 °F or 24 °C to 28 °C). To heat a 5-gallon tank with a tropical fish such as a Betta in it, I recommend the FREESEA Water Heater with LED display. I’ve also reviewed other good heaters for small tanks, but the FREESEA one has done well by me. If the water is too cold, your Siamese fighter may become lethargic, preferring to lie at the bottom of the tank. Improper conditions may also lead to your betta turning pale, which is a sign of disease and a weak immune system in fish.

My Final Words

My size recommendations should be enough to give you an idea of how big a tank should be to accommodate your new Betta.

I hope that you found my guide useful. Feel free to leave me a comment below if you have any questions.

Sharing is caring!

Photo of author


Momchil Boyanov is the Founder and now Senior Editor of AquAnswers. He has over 13+ years of experience in keeping home aquariums as well as providing professional aquarium services. Momchil has had his fair share of adventures in aquarium care. He has made MANY mistakes throughout his fishkeeping journey and thus learned A LOT. Through Aquanswers, Momchil shares knowledge about freshwater and saltwater aquariums with the people within this community.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.