Islandguy11 so you were running with no filter? How often did you do waterchanges?
The only thing i don't like about bettas is that i can't really put more than 1 in a tank without separation....
How about a female sorority? Did any of you tried?
No, that was my staff (local Thai) who doesn't use filtration and I'm not sure how often he does water changes (knowing locals probably not overly often lol). My tank pictured had a built in corner filter (with output closer to bottom of tank, so flow didn't stress betta). I put in the sponge filter on the other side of the tank just to provide a little bit of surface agitation.
And yes with males that's the frustrating issue, only one per tank (and if you use a divider it ideally shouldn't be clear or opaque, as they can still see each other).