Angelfish have a very distinct, compressed body shape. They can reach lengths of about five inches, and measure nine to ten inches tall. A mutation known as "veil tail" can add an additional couple of inches. In the wild they are typically silver with black bars, but multiple colors have been bred in captivity. Their shape and coloration work to camouflage them in the wild.
Angelfish have been kept as pets since the 1920s and crossbreeding for specific colors has been a hobby for decades. If you especially interesting in keeping these little guys as pets, check out some of the article links for information about feeding, water quality, breeding, and behavior with other species (they can apparently be none-to-friendly with other types of fish)