After looking at the video and hearing this description, I'm not convinced that there is anything wrong with the gills. Maybe something is wrong with the opercular flap? Or maybe, given I see lots of bubbles, you have very high DO concentrations and he simply doesn't need to work hard to breathe. The fish does not look like it is in distress to me. It does look like it would appreciate some cover.they appear to be locked shut and he is using his mouth to pass water over his gills