You know, I'm always amazed at how many people have a cure for a disease that no one knows what causes it and start off with the statement that it is incurable!

You can treat the lesions but there is no cure. If a fish is really showing hikkui at such a young age, the prognosis is very poor indeed. Sorry .
Interestingly enough, no one has tried attacking the problem from within? I'd love to experiment with some compounds that work from the bloodstream out into skin layers- several meds of this description. JR