Betta's get over stress ,provided good living conditions and diet, right?
I hope so. My guy is stressed right now, you can tell.
I know this because he is, unfortunately, cramped in a little 1/2 gallon. I am also literally NOT ALLOWED to do water changes every day because I am just 13 and when my parents see me water change, they get mad at me and tell me to do it just once weekly.
There is another issue as well. He is just on one particular side of his tank! The right side, to be specific. He doesn't act lethargic on that side, in fact he is quite healthy and active on the right side!
Could the problem be I put a mirror there a while ago to see him flare his gills for the first time and now he is awaiting for what he though, was another fish, to come back? I know this is kind of abusive, but my relatives recommended it because they wanted to show me the way the species gills are like.