How Many Female Bettas Can Safely Live in a 20-Gallon Tank?

Male bettas cannot live together in the same tank, but housing several females together is possible in the right conditions.

A tank with more than one female betta is a sorority.

Only experienced betta keepers should attempt to maintain a female betta sorority tank.

So, how many female bettas can safely live in a 20-gallon tank?

The recommended number of female betta fish in a 20-gallon tank is five. Keeping fewer than five female bettas together makes establishing a hierarchy difficult. Having more than five female bettas in a 20-gallon tank creates issues with aggression and water parameters due to overcrowding.

how many female bettas in a 20 gallon tank atf

20 Gallon Betta Tank Size and Setup

Tank size is a crucial element for a female betta sorority.

Each betta needs ample space in the aquarium to establish its own territory.

Betta males have a reputation for aggressive behavior. But female bettas are sometimes just as aggressive.

Female bettas establish a hierarchy when placed together in a group. The most assertive betta is usually the leader.

The minimum tank size for a community tank with bettas is 20 gallons. See our review of 20-gallon tanks.

Five female betta fish is a good number for a long, 20-gallon tank. If you want more than five female bettas living together, you must get a larger tank.

Avoid tall, vertical tanks. Tall tanks do not provide enough horizontal swim space for bettas.

Betta fish also need access to the surface to breathe air through their labyrinth organ.

The following chart shows the ideal number of female bettas based on tank size.

Tank SizeNumber of Female Betta Fish
20 gallons5
30 gallons7-8
40 gallons10-12
55 gallons13-15

There is some bad advice in the fishkeeping community about housing a female betta sorority in tanks as small as 10 gallons.

Keeping a betta sorority in anything less than a 20-gallon aquarium is a bad idea.

You will deal with constant aggression in a smaller tank as the female bettas fight over territory. These fights almost always result in a dead betta.

If you want to go bigger, check out our post where we review our favorite 55-gallon fish tanks.

Setting Up Your Betta Fish Sorority Tank

Once you have chosen the appropriate-sized betta tank, it is time to start decorating.

Creating a comfortable environment for your fish increases your chances of success with your betta sorority.

Most betta owners prefer a gravel substrate because it is easier to clean than sand or aquarium soil.

Aquarium gravel comes in a variety of colors for customizing your aquarium. Ensure the gravel pieces are smooth, so they do not injure your bettas.

Adding lots of plants creates a more natural environment for your betta fish.

The plants also help break up the line of sight between your female bettas. This reduces the risk of aggressive behavior among your betta sorority.

Some excellent live plant options for your 20-gallon sorority tank include:

  • Java fern
  • Anubias
  • Betta bulb
  • Amazon sword
  • Java moss

Live plants also help filter and oxygenate the water.

You may also use artificial plants as long as they are made from silk. Plastic plants have sharp edges, which can tear a betta’s delicate fins.

Provide plenty of hiding places in your female betta tank. Hiding spots help your bettas feel more secure and allow them to escape from danger.

Driftwood, smooth rocks, tunnels, and caves all make excellent hiding places for bettas.

Always ensure your aquarium decorations do not have coarse textures or sharp edges.

Take care not to overcrowd your betta sorority tank with decorations. Hiding places help reduce aggression, but your fish still need plenty of space for swimming.

Filtration and Water Changes

filter for female betta in 20 gallon

After setting up your plants and decorations, you must choose an aquarium filter.

Betta fish cannot swim swell in strong currents, so the filter should produce a gentle flow.

A sponge filter works well for aquarium sizes ranging from 20 to 40 gallons. Rinse the filter sponges in tank water when they need cleaning to maintain beneficial bacteria colonies.

For tanks larger than 40 gallons, a canister filter is more efficient.

Canister filters have a higher flow output than sponge filters. If the current is too strong for your betta fish, you may need to install a baffle.

Even the best filter cannot remove all the toxins from your fish tank.

Fish waste, dead plants, and leftover food release ammonia as they decay.

Beneficial bacteria convert these toxins into less harmful compounds. But, there still may be toxins in the water if there are more than the bacteria can handle.

Performing weekly water changes removes excess toxins like ammonia and nitrite.

Remove only 20 percent of the water once to avoid disturbing your tank’s nitrogen cycle. Replace the dirty water with fresh water.

Treat tap water with a dechlorinator before adding it to your aquarium. A dechlorinator removes chlorine and chloramine, which are highly toxic to fish.

During the water change, use the gravel vacuum to remove debris from the substrate.

Temperature and Water Chemistry

Bettas are tropical fish, so they need warm water temperatures.

Ideal water temperatures for a betta tank range from 78-80° degrees Fahrenheit (25.5-27° C)

Maintain these warm water temperatures with a quality aquarium heater.

The heater output must produce 3-5 watts for every gallon of water.

For a 20-gallon tank, look for a heater with an output of 60-100 watts. Place the heater near the filter output for stable temperatures throughout the tank.

You may also use two smaller 30-50 watt heaters, with one placed on each end of the tank. This reduces the chance of uneven tank temperatures.

Water chemistry is also important for your betta’s health.

The ideal water parameters for bettas are:

Ideal Water Parameters for a Betta Fish Tank Include the following:

  • Temperature: 78-80° degrees Fahrenheit (25.5-27° C)
  • pH: 6.5-7.5
  • Ammonia and Nitrite: 0 ppm
  • Nitrate: < 40 ppm
  • gH: 3-4 dGH (50-66.7 ppm)
  • kH: 3-5 dKH (53.6-89.4 ppm)
  • Minimum Tank Size: 5 Gallons

Use an aquarium testing kit to ensure your water parameters stay in this optimal range.

Sudden fluctuations in water parameters are dangerous for your bettas. Maintaining consistent water quality keeps your fish healthy.

Feeding and Nutrition

Betta fish need a protein-rich diet for healthy growth.

These high-quality pellets provide optimal nutrition for bettas.

Besides pellet foods, there is a variety of live, freeze-dried, and frozen foods to add variety to your betta’s diet.

Nutritious food supplement options include:

  • Daphnia
  • Blood worms
  • Brine shrimp
  • Mosquito larvae

Feed your bettas two small meals instead of one large meal every day. Space the meals 6-8 hours apart to allow time for proper digestion.

Remove uneaten food when your bettas finish eating. This prevents an ammonia spike as the food particles decay.

Choose the same day every week for fasting your bettas. A day of fasting lets the fish digest any leftover food and prevents constipation.

4 Factors for a Successful Female Betta Sorority

betta females cohabitation

When choosing female bettas for your sorority tank, there are four factors you must pay attention to.

These factors can determine the success of your betta sorority by affecting how your fish get along.


Female bettas close to the same age get along well with each other.

It is best to get female bettas born in the same spawn, if possible.

Female bettas from the same breeder are already familiar with each other, and they are all the same age.


Personality is a major factor in the success of your female betta sorority.

Even if only one female in the sorority is aggressive, you will have issues with fighting.

Determining the personality of female bettas is only possible by watching how they interact with each other.


Avoid buying sick female bettas.

Many fish illnesses are contagious and can spread to healthy fish in a short period of time.

It is always good practice to quarantine new fish before placing them in your aquarium. Some illnesses may not show symptoms for several weeks, and the fish may initially appear healthy.

Size and Color

Choosing female bettas with different colors and minor size differences is ok. 

Ensure there is no major difference in the size of the bettas because the larger fish may bully the smaller ones.

Sorority Tank Dynamics

betta sorority behavior

Female bettas begin establishing a hierarchy when you place them in the tank.

This hierarchy is important because it helps prevent future fights among the fish. A betta sorority hierarchy is very similar to the pecking order of hens.

Once the alpha female has established dominance, the other females are no longer interested in fighting.

Having at least five female bettas means there is less chance for a betta to get singled out and bullied.

You must add all your female bettas to the aquarium at the same time. Adding the fish one at a time is a recipe for disaster.

When the first female gets added to the tank, she sees everything as her territory. This means when you add the next female, she will likely get attacked by the first territorial female.

By adding all the females to the tank at once, none can claim the entire tank as their territory.

If you wish to add a single betta female to an already established sorority, you must do so carefully.

After the new fish finishes her quarantine, float her in a clear bag or cup in the sorority tank for a day or two. This allows the other female bettas in the sorority to see the new fish and get used to her.

Watch how the other female bettas react to the new female. She may not be a good fit for your established sorority if they seem aggressive toward the new fish.

Have a Backup Plan!

No matter how well you plan your betta sorority tank, it is not guaranteed to succeed.

Individual fish personalities make it difficult to predict whether all the female bettas in the sorority will get along well in the long term.

Even if your betta sorority gets along well initially, there may still be acts of aggression later.

Have a separate tank ready if you need to separate a female from the sorority.

Watch your betta sorority for aggressive behavior. If one female betta displays bullying behavior, you must remove her to a separate tank for the safety of your other fish.

Can You Have Other Female Betta Tank Mates?

In a larger tank, you may add other fish species as tank mates for your betta sorority.

Avoid large, colorful fish and any species known for fin nipping.

Some suitable companions for betta fish include:

  • Neon tetras
  • Plecos
  • African dwarf frogs
  • Corydoras catfish

Once again, watch for aggressive behavior toward the new tank mates. You may have to undergo trial and error to determine which fish get along best with your betta sorority.

Is a Female Betta Fish Sorority Right for You?

A female betta sorority is not recommended for inexperienced fish keepers.

You must provide your female betta sorority with a large tank, many plants, and hiding places.

Five female bettas can safely live together in a 20-gallon fish tank with the right setup.

Be prepared in case your female bettas do not get along. You cannot leave an aggressive girl in the tank with the other bettas.

Check out these other reasons betta fish may end up huddled together in a tank.

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Toni Tedescucci is a freelance writer who loves all animals, especially betta fish. When she isn’t busy writing for Betta Fish Bay, she’s spending time with her family or getting cozy with her cats and a good book.

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