What is TTM
I have simply observed all my anthias in qt, typically 8 weeks. Good opportunity to fatten them as well. None of mine have come with any skin parasites, though body ulcerations have been a problem lately (could be uronema). Personally I see no issues with quarantining a group at the same time; I've done it dozens of times. If fish are coming from the same source, any cross contamination has likely already happened.
Should have added ..... Though I try not to QT fish from different sources together. Trouble with anthias that they can gender transition in QT. had this happen with two groups of bimacs. Had to rehome one of the males, bummer.
I've never had a male turn back to female. Don't think it's possible, though not certain. In my case, since the second males changed in the presence of the first, they largely tolerate each other. I think if you tried to introduce two fully formed males into a new tank things would not go so well. I have multiple Bartlett and Resplendent males as well; though again they all started together as females.
Thanks for explainingTank Transfer Method.
There is a detailed writeup in the fish disease forum but basically you transfer fish to a fresh tank every 3 days (no longer than 72 hours) for 12 days to break the life cycle of ich. You need 2 basic setups which you sterilize between uses. Works excellent for eliminating ich.
TTM + post TTM observation can be a bit of work, but it's a far sight better than having velvet or anything else wipe out your tank again.
I would probably get a replacement RODI unit before I started worrying about bringing in more fish. It will be more useful long term.