The Watanabe's Angelfish, also known as Watanabe's Lyretail Angelfish, is one of the few angelfish displaying sexual dimorphism. The male is an iridescent pale blue. The lower half of the body and anal fin of the male are highlighted by long, horizontal dark stripes and one, horizontal orange stripe extending toward the caudal fin. The female is an iridescent pale blue with a dark dorsal fin and does not have stripes other than a dark outline to the dorsal and anal fins. Watanabe's Angelfish are best housed as a male-female pair in a 125-gallon or larger tank, and are ideal candidates for the deep-water reef aquarium. Acclimation will be facilitated by a dimly-lit tank. The tank should have multiple hiding places and live rock for grazing. Do not keep two males in the same tank as fighting will ensue. The Watanabe's Angelfish are hermaphroditic and difficult to breed. Watanabe's Angelfish seem very susceptible to swim bladder damage. A varied diet of meaty foods such as vitamin-enriched brine shrimp and finely-chopped crustacean flesh, spirulina, marine algae, high-quality angelfish preparations, mysis or frozen shrimp, and other meaty items will provide good nutrition.