15 - 20 years ago, never a QT with no issues. Never heard of anyone else having problems. Perhaps it was an issue never mentioned in polite company. With a few exceptions, all my livestock was adopted off Craigslist. When I got back in the hobby last year, I read nothing but horror stories of tank wipe-outs. So I suspect disease is a bigger problem than it was when I was bought a yellow tang for $15 at the LFS. Now, everything that swims comes from Dr. Reef. Frags/inverts go into 76 day QT, but I have had to reset the clock every time AquaSD had a sale.