Think carefully about why you want to capture bristle worms. They have gotten a bad reputation because they are frequently found eating dead animals, and people assume that the worm killed the animal. Actually, bristle worms are good scavengers, and are only doing what they are supposed to do. IMHO, bristle worm traps are right up there with any of the other non-essential and unnecessary stuff that they try to sell us. Relax and enjoy your worms, they are part of the small ecosystem you have established in your tank!