Help: Bristle Worm identification please

[MaJuBo]

I am new to saltwater and am setting up my first aquarium. I have water, live sand, and live rock. 2 nights ago I noticed what I believe to be bristle worms. I know there is a lot of debate regarding the pros/cons of bristle worms. My question is: do I have the kind that a ‘harmless‘ and just help with cleaning the tank, or do I have the type that attack fish (fire worms/other)?

I did set up a trap and caught ~25 of these guys. Population control is freaking me out as is identification of the species. Then I can determine next steps (since I have no fish/coral/invertebrates yet).

I know the pics are hard to see; my sand is still settling.

 

[Rjukan]

Looks like harmless run of the mill bristleworm to me. These are the bad ones, fireworms:

 

[MaJuBo]

Thank you!!