I guess I didn't understand you - you say you"re looking into creating a betta community, but then you say you wouldn't do more than one, so what were you planning for a "community". The male bettas I have do not have any problem with otos in a small tank. some of the males do not do well in even a large community tank, but it isn't the betta that has been the aggressor. I have found than some of them are just afraid when they have all that space and feel more secure in a smaller area. Although I have not tried it, I would not put more than one female in a 5.5g tank. IMO a female in that size tank wouldn't be much different than a male. I haven't heard anyone on the forum recently who has tried a sorority.