Betta Splendens (more commonly known as “betta fish”) are among the most popular and well-known aquarium fishes. While betta fish have the reputation of being highly aggressive fish, it is possible to house a group of female bettas (also called a “betta harem” or “sorority” or even “girl tank”) together in one tank and still ensure a peaceful environment. However, you must take certain factors into consideration in order to run a happy and healthy tank community that allows your fish to thrive. Sorority tanks are only possible under specific population and gallonage (the water capacity of the tank) conditions; in addition, they must be monitored closely.
Part 1. Preparing for The Female Betta Sorority Tank
1. Consider tank volume.
There is no strict minimum volume for a community tank; however, most community tanks that include multiple fish will need to be at least 10 gallons. Anything under 10 gallons will be problematic due to high bioload (the amount of living organisms in your aquarium that make waste). Make sure you have the space and financial resources to purchase and maintain a tank of this size.
In addition to tank volume, make sure you consider a tank with a hood or lid- betta fish are known jumpers!
2. Understand fish “personalities.”
Like people, fish can, and do, have different personalities. This means that some fish will be a lot more territorial than other fish and that the fish you choose for your female betta community may not make compatible tank-mates.
You will need to prepare a “plan B” in case one of your fish is too aggressive for a community tank.
As a contingency plan, consider housing the overly-aggressive female separately and solitarily. (PLEASE NOTE: It is very difficult to know which betta is causing the trouble and if she is the only trouble-maker).
3. Learn how to care for your betta fish’s habitat
Make sure you monitor temperature, provide treated water, monitor the pH (it should be between 6.5 and 8), add some aquarium salt to the water to prevent your betta from getting diseases and parasites, and change approximately 25% of your tank’s water once a week with treated water (in addition, perform a 100% water change once every 2 months). Keep a clean habitat for your bettas. Your tank needs to be cleaned once a week or once every two weeks if it has a filter. Scrub the inside walls of your tank, but never use soap. Make sure the fishes’ waste and uneaten food that have accumulated in the gravel or sand of your fish tank are cleared out.
4. Learn how to feed your betta
Bettas should be fed once or twice a day. Skip one day a week so your bettas’ digestive systems can take a rest. These fish are carnivores, so make sure you include dried bloodworms or dried shrimp. Keep in mind that your betta’s stomach is the size of her eyeball.[10] Be cautious of overfeeding! Your fish will overfeed if you provide too much food.
Remember that bettas won’t like flake food, even if it is marketed for bettas. This is because they are true carnivores!
5. Recognize the signs of a healthy betta
A healthy betta will be active and alert, will eat regularly, and will react aggressively to any outside stimuli. Common health issues include fin rot (characterized by frayed or disintegrating fins) and Ick (characterized by white spots on fin or body).
6. Include at least 3, and more preferably 5-7 female bettas in the tank
Never keep less than 3 females together in a community tank. If you attempt to keep only 2 females, one will typically assume a more dominant position and will bully the other. Remember that the more fish you intend to house together, the bigger of a tank you will need to purchase. A 20-gallon tank is recommended for more than 5 female bettas.
Part 2. Setting Up Your Sorority Tank
1. Choose dark gravel or a sand substrate to bring out the color on your female bettas.[15] If you want color, choose colored gravel instead; however, neutral-colored gravel mimics the bettas’ natural environment and may help reduce stress.[16]Larger size gravel traps uneaten food. This food can rot and negatively affect aquarium health.[17] To avoid this, choose gravel that is small in size for your betta tank.
2. Find a suitable water filter
You will generally want to look for a water filter that will turn over the water 8x-10x GPH (Gallons Per Hour). Always check the GPH when buying a filter: for example, if you have a 10 gallon tank, you should look to get at least a 100 GPH filter. Consider a filter with a flow that is adjustable. Betta fish prefer a relatively weaker flow of water from the filter.
3. Purchase a water heater for your tank
The water temperature should be maintained in the range of 72 to 80 degrees Fahrenheit. This is the range preferred by aquarium fish, but the ideal temperature is 78 degrees Fahrenheit. A general rule for choosing a heater is to allot 50 watts per ten gallons.[23]Also look to purchase a thermometer for your tank. An electronic thermometer is convenient and easy to read.
4. Find a suitable aquarium water conditioner
If you add untreated tap water to your fish tank, you will be exposing your fish to potentially harmful chemicals. Try a water conditioner that removes chlorine, chloramines, and heavy metals, and simultaneously detoxifies ammonia, nitrites, and nitrates.
5. Add water and allow the tank to cycle for 1 week before introducing fish
Allowing the tank to cycle means allowing it to establish a bacterial bed in the filter. You can also add a biological conditioner to your tank before you add fish. A product such as Cycle Biological Aquarium Supplement is recommended.
6. Purchase fish, and introduce all the girls to the tank at one time, one by one
Buy all your fish at the same time, but introduce them one by one, starting with the one that seems the most passive. This will allow each fish to establish her own territory before the addition of another tank mate.
Make sure all your fish are generally around the same size.
If you can buy “sisters” (or fish from the same spawning), they will have a better chance of getting along.
Consider sticking to odd numbers when stocking your tank. Look to keep 3 or 5 betta fish in a 10-gallon tank or 7 or 9 betta fish in a 20-gallon tank.
7. Ensure your tank is well-planted
Include plants (live or silk will work), as well as features such as driftwood or caves. This will allow weaker females to feel more secure because it breaks up direct sight lines between them and stronger, more dominant females. Providing enough hiding places is required for a healthy sorority tank of bettas.
Each betta should be able to claim their own territory, giving them a place to “patrol” as well as a place to hide.
If you are going to choose fake plants, pick silk plants instead of plastic plants. Silk plants will not tear the bettas’ delicate fins.
Part 3. Monitoring Your Sorority Tank
1. Observe your tank
The females may nip at each other’s fins at first, but once they form a pecking order, this should become less chaotic. However, occasional squabbles between the fish in your community tank are completely normal and should be expected.
2. Monitor for aggressive personalities
Female betta fish will perform a “pecking order,” or dominance hierarchy. This hierarchy will be established quickly. Keep an eye out for any fish that is particularly noticeable as a bully, and also for fish that seem to be constantly antagonized.[39]If you notice one fish that does not seem to be getting along with the rest, remove it from the tank. Being bullied will cause the fish stress and can result in illness.
3. Approach communal housing on a case-by-case basis
There is a chance that your community tank may not work out the first time around: you may have one or two fish that do not get along with the rest. If this is the case, consider removing the problematic fish from the tank as soon as you recognize an ongoing issue.