I have a reddish brown colored brittle star, and never ever thought of him as something that would eat my fish. Maybe I need to look him up to huh! I bought 4 fire fish goby's once, and we only saw 2 of them come out of the back just a little bit. They seemed scared to come out. I never saw any of them after that one time. My 'Brit' lives under any and all of those rocks, but I don't believe that the browns eat fish. I guess I should do some reading. I haven't lost any fish before or since, so they must have just died! Try to get your LFS to at least give you store credit for your little green monster! To bad they don't refund the fish he has in his belly to! We all find these things out the hard way, don't we? Bummer!!!