Velvet

[Aquattro]

Originally Posted by Doug

If the fish one has left beat it and seem to be immune, how long until you can add new fish. Can it hang around forever? Will my immune fish still carry the parasite? And so forth.

I can't read back through all that mess, so I'll pick up here. If you had a fish exposed, and not treated that appears to have developed an immunity, I would not add other fish to the tank with it.
Remove it, treat it, and leave the tank for 3 months. Then add newly QT'ed fish to the system.