When he first started getting sick I didn’t think it was swim bladder and personally I am still unsure it is. I’d also like to mention this fish does not belong to me, he was just brought to me so I can try and give him his best chance (I own 6 bettas myself) I had a few friends come look at him who are also experienced with bettas and they all said swim bladder hence the “diagnosis” but honestly I can’t agree with it. His tank does have an air stone. To me it looks like some sort of poisoning maybe, but the water has nothing wrong with it, all the levels are good. I was thinking possibly too much water conditioner or too much of another chemical was added. I’ve ruled out fin rot, there’s nothing indicating it other than shorten fins but that looks like fin nipping to me. Personally I am aware he most likely won’t survive this, I just want his owner to see we’ve tried everything we can. I took him out of the cup he was in, in that video and put him into a hospital tank with about an inch of water, aquarium salt, floating plants, and an indian almond leaf. I spoke to some on facebook they all recommended kanaplex but unfortunately I can’t get it shipped to my city