Betta Fish Tank Size. A Complete Guide.

You go to the pet store and see all of the bettas in tiny plastic bowls or cups. You are told that Siamese fighting fish or bettas do just fine in such small tanks. You buy one, along with a bowl and some food. Soon afterward, your betta gets sick. What happened?

Bettas can live in tiny bowls, but not as well as in larger aquariums. They need room to exercise. They need larger aquariums where the water does not foul so quickly. They need a heater and a filter, something that’s almost impossible in a one gallon tank.

If you remember nothing else from this article, remember this – bettas need a heater and a filter. They are tropical fish, needing temperatures from 78 to 80 degrees F.

The Size of a Betta’s Natural Habitat: Spoiler – It’s More than One Gallon

You may have been told that bettas live in mud puddles in their natural environment. They can, but only for brief periods. They are able to breathe oxygen from the air, thanks to a nifty piece of anatomy called the labyrinth organ.

Bettas in the wild live in drainage ditches, ponds, rice paddies, river deltas and other swamplands in Southeast Asia. They live in territories of about three-square feet or one square meter. That’s just over 20 gallons.

The Only Time to Use One Gallon Tanks

Not only did the pet store industry tell us that bettas could live in containers of one gallon or less, so did many books on betta care that were published before the 2000s. Books talked about breeding operations where individuals lived their lives in one-gallon jars.

We know better today. Bettas need a heater and filter to stay healthy and happy. However, there are times when a 1-gallon tank can help. These can be used for emergencies such as:

  • A place to keep a betta in while moving house.
  • Keeping a fish in while waiting to go to a new home.
  • Having a temporary place for a male if he’s fighting with the other fish in a community tank, or a female if she’s fighting the other females.
  • Having a place for the betta should the aquarium break or start leaking.

Never Use Anything Less Than Three Gallons

Although three gallons is not ideal, it’s the absolute minimum tank size one betta can live in comfortably. This is large enough for a filter, heater, real or silk plants, and small decorations so that the betta can swim around and find a nice hiding spot.

Three gallons also make a good size for a quarantine tank or a hospital tank. If a betta in a community tank looks sick, it’s best to separate him or her and treat them in a hospital tank rather than have the illness spread to the rest of the fish in the tank.

If you also have a betta in a community tank that got hurt from a fight with another fish, it’s good to pull that fish out of the community tank into the hospital tank. When it is better you can either reintroduce the fish back into the community tank or find another tank where he or she is not bullied.

Five Gallons Is Okay

A 5-gallon tank is a happy medium between having a home large enough for a betta to have some fun in, and small enough so that it can fit into many homes. This is large enough for one betta, male or female.

Bettas become livelier in a larger tank like a five gallon. These fish are far from the apathetic creatures hanging about in tiny pet store bowls. They usually become more vivid in their coloration, too.

Bettas become more interested in you, too, when they are in a larger tank. You can see them following you when you move about the room. They may even come to the surface and bed for food, just to give you a hint.

Can You Put More Fish in a Five Gallon?

It’s tempting to place more fish in a five-gallon tank than just one betta. Even adding two neon tetras seems like it would make the aquarium more interesting.

However, I strongly discourage this idea. Just keep the betta by himself or herself. Small fish like neon tetras tend to need schools of at least six fish to feel secure and healthy. This means that they should be kept in an aquarium that is at least 10 gallons large.

Bettas are unpredictable in what fish they will get along with, so adding any fish in such a small tank just invites fights.

The Ten Gallon Tank

A 10-gallon tank is a great size for one male betta and a small cleaner fish like a cory cat. They also can make a good home for three female bettas. A tank full of female bettas is called a sorority tank.

One advantage of larger tanks is that you don’t have to clean and change the water as often, as long as you do not overstock the tank.

I know the general rule is one inch of fish per gallon, but in my personal experience, this rule should be two gallons per inch of fish. There needs to be room for the fish to set up their territories. Also, there always seems to be that fish, like a betta or a cory cat, that grows larger than usual, making for more poo to clean up, which can change the water quality drastically.

The Best Tank: The Twenty Gallon

My best experience of keeping fish has been with 20-gallon tanks. This gives the fish a lot of room to explore. Since I’m on the lazy side, a larger tank with a good filter means I do not have to do partial water changes so often.

You can keep one male betta and a few danios and one cleaner fish. Or have a few females and perhaps a few danios. Danios and bettas generally get along well. The only problem is that danios swim faster than bettas, so you need to make sure the bettas get their fair share of the food.

What Size Tank is Too Big for a Betta?

You can have a tank too small for a betta, but you can’t have a tank too large for a betta. It is a common misconception that bettas will die from stress if placed in large aquariums. There have been bettas that absolutely thrive in huge 125-gallon aquariums. For bettas, the larger, the better.

However, you can also have a tank so large that you find it hard to clean and care for. A 125-gallon, for example, needs one or more filters, a lot of water conditioner, and much more time scraping clumps of algae from the sides. Do you have the time and money to commit to caring for such a large tank?

So, What is the Best Tank Size for Betta Fish?

Any aquarium should try to mimic the conditions fish would have in the wild. Wild bettas live in territories about three feet square, or one square meter. This translates to just over 20 gallons.

Although a 20-gallon tank best mimics wild conditions, the size may be impossible for many people’s homes. The bare minimum one betta should live in is a 3-gallon tank.

If you need some inspiration on setting up your tank, please read our article on unique ideas for your betta tank.

If you want to learn more about betta tanks, please visit our collection of articles here.

About the author

Hi, I am Rena.
I grew up in a house surrounded by fish tanks.
I have spent my life caring for and writing about fish.
I have studied journalism and worked for online and print magazines.

You can find the articles I wrote here