September 4th noticed my Whitetail Bristletooth Tang had spots on his fins and my my Black Ice Snowflake clown was swimming at top of tank. Looking closer at the looked like he was dusted in powder. Tang was still eating/swimming fine but clown stopped eating. Sent video to LFS and he said looked like ich and sent me PolypLabs Reef Medic. After treating for a week there was no change. He came out and said it looked more like velvet and to continue with the ReefMedic but to up the dose. He took the clown with him to put in their hospital tank (I don’t have quarantine). Tang stayed because he was eating and swimming normal. Fast forward to today, Tang still looks the same but he’s eating great, breathing and swimming fine. Everything I’ve read makes it sound like my Tang should be gone by now. I have a Reefer 425xl, mixed reef tank. Other inhabitants are Melanarus Wrasse, Mccokser Wrasse, male Lyretail Anthias and juvenile Black Ice Snowflake Clown...they’re all eating/swimming fine too (maybe because of Reef Medic) Never needed a quarantine tank, because I never put anything in my tank unless it came from my LFS. I know their system with their new fish & coral. Of course, the first time I add a coral from somewhere else, this happens. I did dip the coral not realizing it does nothing to kill any eggs. Do I need to remove fish from tank? If so, how quickly can you set one up? Also, how do you eradicate parasite from main tank? Any advice would be greatly appreciated.