A Polychaete Word of Caution

[naesco]

Zoaelite
I am sorry to see that you are suffering losses especially to a reefer that takes the time to specialize as you have.

But, I think your are giving the bristle worm a bad rap. They are scavengers not predators on coral and zoas. They are an exceptionally benefical scavenger and harmless to reef animals.

I can think of two possibilities.
1. Your zoas are dying from some disease and the bristle worms as scavengers are cleaning up the dead tisse. That is the job they were doing that night.
2. That you do not have brisstle worms but you have bearded fireworms (hermodice carunculata which are predators and love zoas. Thankfully they are very rarely seen in the hobby.