I have used epson salt on Pop Eye, and had great results. It sound like the puffer has Oodinium (also known as velvet disease). It likes the eyes and gills of many of out fishy friends. Epson Salt won't work on this. By the time you get this message he may be gone, or not. If the fish is in an invert tank, and it is, just keep the temp stable and the fish well fed. Then cross your fingers. The disease is very contagious. I've never seen anything work on it in an invert enviorment. In fish only systems I would reccomend copper @ .15 ppm. Remember the decimal in .15

Fish get real sick during this time of the year because of the temp swing. So keep it steady @ 78.