Well, it may depend on the anemone and where it came from, and what you have already, but many of us nem keepers do QT new nems just to observe, some species are known to travel w/ bacterial infections and can pass that to other nems, so especially for a magnifica, gig, others prone to bacterial infections yes we would qt, and if needed treat w/ cipro.
There is a cipro and qt sticky above in nem forum that explains in more detail.