How Many Betta Fish Can Live in a 20 Gallon Tank? A guide (2023)

Keeping and breeding betta fish is an incredibly popular hobby these days, so if you have a spacious 20-gallon tank, you may be wondering how many of these beautiful fish you can keep.

Can you keep several male Siamese fighting fish together in one aquarium? Do female betta fish fight? And what special modifications do you need to make to your tank to house more than one male betta?

Read this guide to find out how many betta fish can live in an aquariumTank of 20 litersand more!

Is a 20 Gallon Aquarium Big Enough for Betta Fish?

Bettas are generally considered nanofish and are often kept in small aquariums of about 5 gallons. I've even successfully kept a male betta and a few suitable companions in a 10 gallon tank, and there was plenty of room for him.

That said, wild bettas tend to take up a territory of about 3 square feet, so if you can get your fish a larger tank that's even better, and 20 gallons is pretty much the perfect tank size.

Since most types of betta fish only grow to be 2 to 2.5 inches long, they clearly don't need a huge aquarium physically.

However, these extremely territorial, aggressive fish do not like to live in cramped spaces with lots of company. In their natural habitat, betta fish are solitary creatures, interacting with other bettas only during spawning or during encounters with rival males. Keeping that in mind, you can see that a 20-gallon aquarium will provide plenty of room for betta fish.

How Many Betta Fish Can Live in a 20 Gallon Aquarium?

Several critical factors determine how muchbetta viscan live in a 20-gallon aquarium, and we'll discuss them below.

Man or woman?

The sex of your betta fish is crucial in determining how many of these beautiful fish you can keep in your 20-gallon betta aquarium.

Both sexes are somewhat territorial, although in my experience males are much more aggressive than females when it comes to protecting their adopted place. If you try to put more than one male betta in the same tank, a fight is virtually guaranteed and these fish will fight to the death to defend their territory.

However, I have kept small groups of up to five female betta fish in the same tank several times without incident.

In fact, you should not keep two female bettas together, as one will likely try to bully the other. However, keeping a group of females often prevents that.


So now you know that you cannot safely keep more than one male betta fish in the same tank, no matter what size tank you have.

Don't despair though! It is possible to keep several male bettas in one tank if youuse dividersto split the tank into separate compartments for each fish.

As you know, if you use a mirror to exercise your betta and encourage it to flash, even the sight of another betta fish through glass can trigger a seizure. Therefore, you should use opaque dividers that extend to the very bottom of the tank bottom. This way the fish cannot see each other and they cannot swim under the partition.

The number of dividers you use will depend on how many male Siamese fighting fish you want to keep in your 20-gallon tank. Most hobbyists use three dividers to house four male betta fish in a 20-gallon tank, which is fine, provided each fish has at least a 5-gallon space.

Potential problems

The use of dividers presents the aquarist with a few challenges.

  • Yourfiltration systemmust be powerful enough to pull water through each section and around the entire tank.
  • The dividers should fit snugly so the bettas can't get into each other's separate compartments.
  • You must be extremely diligent when it comes to keeping each compartment clean and maintaining consistent water parameters throughout the tank.
  • It can be difficult to maintain a constant, stable water temperature in a tank with dividers. Bettas are vulnerable to temperature shock, which can be fatal, so you must have a heater powerful enough to keep the water warm enough throughout the tank.

However, if those challenges don't faze you, keeping more than one male betta in a 20-gallon tank may be an option for you.

Tank maintenance

The more fish you keep, the more important that iskeep your aquarium cleanand well maintained. That's because more fish waste and food scraps can build up quickly, producing ammonia and other harmful chemicals as it decomposes.

You have to perform in a busy tankweekly water changesand keep track of filter maintenance. If you likeliving aquatic plants, prune overgrowth and dead leaves as needed.

Aquarium decoration

Wild betta fish live in a densely vegetated natural environment, so you should try to replicate that as much as possible in your betta tank. These fish also need plenty of hiding places such as caves and rocky overhangs that they can claim as territory. That is of course difficult to achieve in a tank with dividers.

In a betta sorority aquarium, you have more room and room for things like driftwood, pebbles, smooth rocks, and lots of plants to create a nice tank.

Keep in mind that a decorated aquarium can be a beautiful sight, but anything you put in it takes up precious swimming space for your fish.

How many female bettas can live in a 20 gallon tank?

If you want to keep a female betta sorority tank, I recommend keeping between four and five fish.

Don't forget to give the fish lots of plants and hiding places where they can hide and feel safe.

Female bettas tend to bicker among themselves from time to time, so giving them a place to hide is essential to a harmonious community.

Male Betta Fish

You can keep one male betta fish in a 20-gallon aquarium. This tank size provides plenty of room for the fish and lots of attractive decorations, so it's a win-win situation.

If you want several males you will need to use dividers and you can have four or five fish.

Whether you keep a single fish or several fish separated by dividers, you must provide them with sufficient hiding, resting and planting areas.

Male bettas like to build bubble nests, so floating plants are a great idea, provided you leave enough space for the fish to access the surface of the water to breathe.

Can You Keep Male and Female Betta Fish Together?

Although it may seem like a good idea to do soput a male and a female betta fish together, which is often a recipe for disaster.

Male bettas can be extremely aggressive towards a lone female, biting or chasing them around the tank.

This puts stress on both fish, sometimes leading to injuries and other health problems. So rather than putting one fish of each sex together, it's usually best to keep them apart.

That said, I had a dispute of bettas with one male without any problems. Perhaps thefish behavior simply depends on personalityof the individual male and the dominant female.

Avoid overfilling the tank

If you decide to keep only one male betta in your 20-gallon tank, you may want to add a fewsuitable tank matesto keep him company.

Although male bettas are solitary creatures, they are intelligent, curious fish and appreciate the mental and physical stimulation provided by a few peaceful tank mates.

Bottom-dwelling fish species can be ideal tank mates, includingCorydoras catfishand small plecos, which usually work well, as well as peaceful fish that live in the middle part of the water column.

Be aware that some tetra species, such as neon tetras, can be snappy and harass the betta, and large, aggressive fish can cause problems by bullying the betta.

Usually larger shrimp and ornamental snails make excellent tank mates for betta fish, they keep to themselves and provide a valuable cleanup crew as a bonus.

Final thoughts

Did you enjoy our guide to how muchbetta viscan live in a 20 gallon aquarium? If you did, remember that sharing is important and hit the Share button above!

Male bettas are very aggressive tropical fish that cannot live together unless you use opaque tank dividers to create separate habitats for them. However, you can safely keep a small betta sorority or single male betta with a few suitable tank mates.

Do you keep multiple bettas in one tank with dividers? Tell us how your fish friends are doing in the comments section below!


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