Are you talking about a golden Pygmy?
If you are I had one for many years and he never ate anything I put in the tank, he only ever ate of the rock. He spent 85% of his time in the rock, but none the less a great fish never bother any coral; I had him for 4 years.......
Then one day I picked up a sunburst anthias and the angel took a liking to his eyes. Next day he did the same to my six line I had for 5 years. I actually saw this happen. I then took out the angel and let LFS store have him. Just my experience, if it is the same angel that is.