Porcupine puffer ill?

ok, i have a porc. puffer at work, whose had this ball like fungus ill call it for about a week and a half now, and the treatments our store allows us to treat with is definately not working. we are only allowed to use Clout, which i think sucks, even for freshwater, and it doesnt treat his symptoms. i know this kind of fish is prone to getting ill. the reason we re not allowed to use other medicines, is because of the copper and other metals they have in them, which can hurt inverts and other saltwater inhabitants (some salt water customers still use the water in the bag and add it to their aquarium, so we dont want to hurt their system. what im wondering is, will a fresh water dip help get rid of these ? theres 4 of them. other then that hes eating like a pig and being very active. im doing water changes to make sure his water is healthy. i just dont know what else to do! hes not getting worse, but hes definately not getting any better.