Dwarf Angelfish are generally bold in nature.  For that reason, they shouldn't be kept together unless they are in male and female pairs.  Dwarf Angelfish dominate their environment and tend to stay front and center.  They are very popular for their bright colors and ease of care.  Dwarf Angelfish graze the reef looking for algae.  Arguably the best feature is that most dwarf angelfish stay relatively small which allows a wide variety of suitable environments.