I'm not sure if Gold Flake is reef safe at all. I have a Gold Flake's close cousin, Griffis Angel, that is about 4-5 years old. I got it when it was about 2 inches long and could barely eat anything larger than the plankton. Due to some early childhood disease, his/her normal growth was sabotaged so his/her size remains small, like 4-5 inches now. Some on-line stores declare that Griffis is as reef-safe a larger angelfish as can be. However, this angel was a model citizen until one day he/she decided that coral is gourmet food.
Introduce Gold Flake at your own risk.