People view then leave a post because they dont know whats wrong and hope someone more knowledgeable comes along.
Maybe another post in the emergency section may have got it noticed quicker.
You will need to tell us more about the tank and water quality readings. How long did you ahve them and was there anything new introduced before he was ill. I know its too late now but whatever ailed him may pass to the other. With the gills always puffed out it could either be a water quality problem or a parasite infection to bacterial gill problems.
Were his gills inside paler than usual and more sticky looking?
About the behaviour with the other fish, do you have ornaments in the tank as he may have been needing to scratch himself and only had the female to do it off.
Sorry you lost him though.