Six days ago I added one afra jalo reef and two melanochromis exasperatus I had bought and the next day noticed the two exasperatus had tiny black specks on their body and fins. It looks like they were sparsely peppered but doesn't it seem to bother them. I added MelaFix and PimaFix three days ago and yesterday added 1T. salt per 5g. (60g tank). I have no idea what it is or if it is contagious. I have about 18 other mbunas with them and they are fine. I need to indentify this and find the proper treatment.