I have an 8", maybe even bigger, bristleworm in my 55. I love him, for the simple fact that he eats lots of hair algae and seems to work on detritus too. He is ugly, but luckily only comes out at night... Their was a good thread the other day talking about how 99% of bristleworms are actually beneficial. The decision is up to you, but in my opinion, as long as they are small, for u stated u had a 24, I would keep them.