Bettas are highly territorial and can challenge other fish in a community aquarium. Female bettas are known to get along comfortably, while males will fight each other. It's a good idea to start with one fish and then introduce any additional friends slowly to keep the tank happy. Smaller fish that are not brightly colored aren't seen as a threat to bettas. But be warned — they will attack other fish if feeling intimidated. Bettas also like having a spot to hang out or hide when feeling stressed, so add a big rock or cool decoration to your tank.