Hate to ask, but until lately you were usually in the salty section.
By now reading through posts, you knooow your goldie should be in a 10- 15 gallon all by its self..larger with company right? your oranda is not in a tank smaller than that is it?
And how long has that particular tank been running? And how good is the filtration?
Those aside, what temp were you keeping your goldie at and what is his diet? Those are the next two factors that make your golds pop up with crud.
Specially too warm. My grandfather's showfish used to get gross in the summer. His ponds were chilled , his tanks were not. I wish I had helped treat them and was a better diseasse troubleshooter... heh, I had thought that
was the dreaded "ick". They would end up sporting slimy fur coats by the weeks end. Only the moors and orandas and such. Specially in grow out tanks. His koi were alway stupendous.
Kanacyn is prolly the best of today's available anitbiotics, it is not yet overused ...or good ole jungles fizzy tab for fungus.
But golds also get fuzzy spots if there has been a pH crash. And maybe there is something bacterial or an injury and the fungus is overlaying it.Golds respond well to the old standbys like copper and salt. They can take a prety strong salt bath (a separate from living quarters dip)
Good ol Salt will often cure bacterial AND parasitical AND fungal problems at the same time. On a good sized gold, Iodine can be used to swab a sore and will often sort out a bacterial AND fungal problem simultaneously. You can use an antibiotic food - such as Medigold - AND an external med at the same time.
if fungus cure is like super fungus plus it has malachite green and/or formalin and your cycle is now toast.
also with golds..change water..then change it again. Just think "coldwater discus".