I will see if the spots "move"Those spots look a little large to be ich, but ich often causes a generalized reaction in puffers, producing extra mucus. The trick would be to compare the fish from yesterday to today using photos. If you see spots in different areas day to day, then it is likely ich. If the same exact spots are there for more than 36 hours, it isn’t ich.
What other fish are in the tank? Do you have a treatment tank you can use to treat the fish with copper?