I've been experimently lately since I've had so many bettas and wanted to branch out a little. So first I moved a male betta to my 55 gallon with
1 angelfish, 3 gouramis, platies, cories, albino rainbow shark, 2 female bettas (1 hides all the time). And a week later everyone is happy and healthy! I was shocked, constantly watching the tank but even when he went up to the active female, no aggression from either. Just a little flaring then went on their ways. Of course my eyes are constantly peeled for any aggression just in case. Then I have my 29 gallon split with one male in a 10 gal area and another male in 20 gal. With the 20 gal there is a ADF and mystery snail and 10 fancy guppies. Yup, fancies, well 7 fancies and 3 endlers. All is well! I think it definitly depends on the individual betta but I'm so happy it's all working out! I plan to make the who 29 super planted with lots of driftwood! Just thought I'd share!