Watanabe's Angelfish

Geographic Origin and Biotope: Tropical and subtropical Indo-Pacific, from Taiwan and the Ryukyu Islands to the Cook and Tuamotu Islands. Inhabits current-swept outer reef slopes at depths of 21 to 81 meters.

Taxonomy and Morphology: Member of the family Pomacanthidae. Reaches a maximum length of 15 cm. Features a slender, compressed body with a deeply forked swallowtail caudal fin. Sequential protogynous hermaphrodite.

Social Behavior: Peaceful and highly active water-column swimmer. Forages constantly in currents in small haremic groups. Highly prone to jumping when startled.

Coloration and Sexual Dimorphism: Striking sexual dichromatism. Males are pale blue with horizontal black stripes on the lower body and a yellow stripe near the anal fin. Females are uniform pale blue with black margins on the fins and head.

Aquarium Setup: Requires an aquarium of at least 500 liters with vast open swimming space and strong, well-distributed currents. A tight-fitting lid is mandatory as they are exceptional jumpers.

Diet and Feeding: Carnivore/Planktivore. Feeds exclusively on zooplankton in the wild. In captivity, feed 3–4 times daily with mysis, brine shrimp, calanus, copepods, and high-quality pellets.

Water Quality: Demands stable parameters. Temperature 22–26°C, pH 8.1–8.4, salinity SG 1.020–1.025, GH 15–25, and KH 8–12. High biological load requires robust filtration and skimming.

Compatibility and Tankmates: Very peaceful toward other reef fish. Completely reef-safe; it will not nip at corals or sessile invertebrates. Excellent in pairs or small harems.

Aquarium Reproduction: Undocumented in home aquariums. Broadcast spawners releasing pelagic eggs in the wild.

Risks and Diseases: High incidence of swim bladder issues if decompression was poorly managed during capture. Susceptible to marine ich (Cryptocaryon) if stressed.