A simple freshwater dip of any new fish before entering your QT or main tank can prevent this parasite from being passed along. Once it is establised in your main tank it can be hard to get rid of not unlike regular ich even though they are not the same disease. Also black ich is not very debilitating, but left untreated can eventually claim the life of the fish by allowing other infections to set in. Freshwater dips are recommended every three days, each time erradicating parasites that were not on the fish before. Freshwater dips can kill this parasite unlike regular ich, where its just to releave the fish of some parasites until other treatment can be performed. Usually, if you remove the host tang(s) from the tank for 30 days the disease will die out. I am going to try some Prazipro myself in my tank to try to avoid removing any of my fish to QT. Prazipro is a dewormer that claims to work on Tubelarins (sp), it claims to be reef safe and safe for your biological filter, although it will kill any worms in your tank good, bad, and ornamental. I will let you guys know if it works, I sure hope it does.