i had a huge bristle worm in my tank recently and i know they can reach plaque proportions really quick i caught a few of the bigger ones, i got afraid they would start eating my zoo's,anyway that may be one just keep an eye on it i know they do a good job keeping the tank clean but if you start to see more like that,i would start to worry ,i just got a sixline wrasse and i havent seen any since'' they're are different types of bristle worms and the ones you dont want in your reef tank are the coral eating fireworm(bearded fireworm)the type i have in my tank are the aquarium fire worm and from what ive read they are beneficial scavengers?