ive seen payara in the shedd aquarium in chicago with the white dot on eye. If these guys cant get rid of it, i would bet its hard to treat. 2 of my 5 tats have the white dot on the eye and have had it since i got them over a month ago. so im thinkn it might be permanent. Melafix or pimafix wont hurt em, i use it on all my fish. if the fish is eating and its not gettin anyworse then i wouldnt worry about it.