Hi, It's quite difficult to see but it looks like a cocoa damsel (Stegastes variabilis) although i've never kept this species I have heard that they are fairly tough and can be cared for like any of the other small damselfish. I should have said that only the juveniles look like this.
Not sure it was any of those. Was in the sea in the Carribean. Very purple looking. Could have been a damsel. Need to get myself a better waterproof camera I reckon!
I would of gone along with the yellow damsel myself but after you saying about the color....mind you they do change color slightly under stress if i remember rightly, hope you find out what fish it is as she looks great!
