Originally Posted by
surfinusa
i read that they can kill and eat fish but very small fish like 1 inch sometimes bigger but a book said something about eating them sounds weird but a very large bristle worm could at least thats what this one book said
There are over 10,000 species of Bristle Worm.
There are two species I know of that can eat a small fish.
One of the two needs to be huge (measured in feet) before it can capture a 1" fish and it isn't likely to be found in a hobbiest's tank.
The other has been reported but it's quite rare for it to be in a saltwater tank. It builds a mucus bubble around a sleeping fish. The fish either suffocates in the bubble or there's some type of toxin in the mucus that kills the fish, perhaps both. The Bristleworm then proceeds to eat the already dead fish.
The vast majority of Bristleworms found in an aquarium either filter feed, eat carrion or eat detritus. These are the worms that are considered beneficial or desireable.