Looks like its a white damsel. Deffinately not an anthias... I've seen white damsels before, but it looks like it was once blue and is now white, but that may just be the blue reflecting off the bottom.
I think you're right. I looked at pictures of Paraglyphidodon melas and it definitely looks like one (especially the adult one). When you look at mine from certain angles you could see a slight darkness. I wonder if he'll turn any darker.