well, a fireworm is a bristleworm no? one has toxins, one doesn't, though I'm now allergic to bristle worms, since I kept plucking their fiber-like barbs, out of my skin, every time I handled my rock work.
Heh, there must be hundreds of species. Get a coral banded shrimp to eat his friends. If you found one, there must me more in there. A wrasse will also work, but they only eat what will fit in their mouths. A shrimp will chew anything. In the long run, you could get both, a 6-line wrasse and a pair of coral banded shrimps. Make sure you get a male and female, they do not look alike.