Bristleworms in great numbers were not put there by the easter bunny---they cannot reproduce without being fed; and if you're feeding that many you're apt to see a tank crash if they all disappear...not from the worms, but from the rotting food. Rot and slime or things of so small a particulate size it's near-slime---are ALL they can eat, since they do not have jaws, cannot bite. They have a tiny soda straw for a mouth, right to the gut, and if it's not slime, they can't do much with it. You'll see them make off with a small food pellet, sucked up against their mouth, but they have to wait for it to dissolve. The bristles themselves may stick in a fish: I've seen firefish get a real faceful; but they fall off after 3 days, no big deal. THey ARE a reason to wear gloves while handling rock: WE get sensitized to them over time (as to corals, etc) and they can be a problem for us, but they are too valuable a detrivore to eliminate from the tank. Crabs and snails cannot do what they do nearly as efficiently, into the smallest crevices.