i add a capful of kent marine micro vert twice a week for my feather dusters and other filter feeders (my gorgo loves it as well). i tried spot feeding them once and it just freaked them out. as for tangs, it's a risk... but trigger fish are a bigger risk
all depends on the fishes personality...this might be a silly idea (or at least unpopular), but califishdude, if you get a few feather dusters, and your tang attacks them, you could always put them in your refugium if you got one...they're not going to eat your bugs after all...
and travis, you probably had a bristle worm that was happily living near your feather duster, when you moved the feather duster it just freaked the worm...he's probably hiding somewhere else now instead