It’s quite common to keep a betta “sorority, ” that is, a group of female bettas. Female bettas are aggressive, though less so than males, so you need lots of space and lots of hiding places like caves, driftwood, and plants. A rough rule of thumb for betta sororities is to start out with 10 gallons for the first fish, and add 5 gallons for every additional fish.
Many have successfully kept a single male betta in a community aquarium. To do this successfully, again, make sure you have lots of space for everyone and plenty of hiding places. Make sure the rest of the community is well established, and most importantly, does not contain any fish that is slow moving and has long, flowy fins, or any fish that is aggressive. I’m assuming you’re aware of other compatibility issues for community fish. The betta will attack slow moving fish with long, flowy fins, and aggressive fish might attack the betta, which is fairly slow moving and has long, flowy fins. The betta must be the last addition into the tank. Watch closely for any signs of aggression over the next few days, and be ready to remove the betta if necessary.
You can put a male and a female betta together if you want to breed them, but this has to be temporary because the male will attack the female. Only keep them together long enough for the female to lay her eggs in the male’s bubble nest, then remove the female. Prepping bettas for breeding is an entire different topic.
It is possible to keep more than one male betta in a single tank, but this must be done very carefully and is not always possible depending on the personalities of the individual bettas involved. You need a lot of space and a lot of hiding places. Plants and driftwood in particular are great for delineating territories and for breaking up lines-of-sight between fish. Have at least 10 gallons per fish. Introduce all fish at the same time, so that there are no new fish intruding upon established territories. Introduce them in a darkened room so that the fish are more focused on their surroundings and less focused on other fish. When feeding them, make sure each fish has its own feeding spot so there is no competing for food. Watch the fish very carefully for the next few days. If there is any sign of aggression, be ready to remove fish into individual tanks.
If you are planning on attempting any of these, I hope you already have experience keeping individual bettas or freshwater tropical fish in general. If not, there are a lot of resources on the internet that are better than Quora. In particular, you will need to learn about nitrogen cycling. Use websites like or to learn more about fish keeping.