Well, since you put bettafix in it, I assume that there is already something wrong with the betta. Bettafix is a medicine for antibacterial diseases, so I would hope that he is looking and feeling better.
If he looks like he is gasping then do a small water change. You can use the betta fix at half the perscribed dose as some betta's don't do well with it. What are you treating for btw?
. Bettafix is a medicine for antibacterial diseases, so I would hope that he is looking and feeling better.