a lot of people dont, including myself (whos patient enough to qt their new prize coral?), but you technically should, some corals and inverts can carry parasites that you qt fish for, but they are much less likely to posses them if they were bought from a place that has independents for fish, corals, and inverts, because the parasites usually die off when the supplier qts them (im talking about big suppliers like SWF and such). but they could be reintroduced if they are then put into a mixed system at the lfs.