Serpent/Brittle star

Ok I seem to maybe have a problem in my tank within my live rock. Correct me if I'm wrong but serpent and brittle stars may prey on fish right? I have had the weirdest things going on today I had a royal gramma die. But strangely a week or two before I had a fire fish die. My royal gramma always hid in the rock. A lot of times I see a star fish that looks like this..http://www.3reef.com/forums/inverts/discovered-brittle-star-41778.html the one on the right. but also looks sort of like the attachment... im not sure maybe they are the same things. Please ID this invert maybe i should've put it under ID This ! well oops.
Thank You!

 

Looks like a Brittle. I have a serpent star and they only eat fish that are already dead. They are excellent for clean up and extremely hardy. I am pretty sure brittles are similar to serpents

 

I have a serpent star (black/white like your picture) and a HUGE brittle star - I've had them both for many months and neither have ever bothered a fish. My only fish losses in the last 7 months have been from jumping out of the tank. The starfish both come out and night and feed on the detrius/icky dead stuff. Like I said, my brittle star is HUGE and could have wiped out the entire tank if it was prone to fish attacks!

Could you have a hitchhiker crab going after your fish? Just a thought.

 

The green brittle star is the most known to prey on fish.

 

Yep, my friend had a green brittle and it ate all the small/weak fish.

 

Alright thank you guys! At least now i know it probably isnt the star.