Watanabei Angelfish: The Elegant Lyretail

The Watanabei Angelfish (Genicanthus watanabei) is a striking and relatively peaceful marine fish belonging to the genus Genicanthus, commonly known as Swallowtail or Lyretail Angelfish. Unlike most large angelfish, Genicanthus species are planktivores, spending their time hovering mid-water to feed, and are generally considered reef safe with corals. This species exhibits strong sexual dimorphism (differences between male and female), making it a visually dynamic addition to a mature aquarium.

Native to the deep outer reef slopes and drop-offs of the Western Pacific, the Watanabei Angelfish requires excellent water quality and plenty of open swimming space. Due to their tendency to be shy and their need for frequent feeding, they are recommended for Intermediate to Advanced hobbyists.

Sexual Dimorphism (Male vs. Female):

• Female: The females are predominantly a beautiful pale blue or silvery-blue color across the entire body. The key identifying feature is the presence of three horizontal black bars running along the back and a black margin on the dorsal fin. Their tail fin is typically rounded or slightly lyre-shaped.
• Male: Males are generally larger than females and lose the distinct black bars. The male's body is a similar silvery-blue, but the margins of the dorsal and anal fins are extended and intensely black or deep blue. The most distinguishing feature is the presence of thin, irregular blue to black lines or squiggles that cover the face and lower body. The tail fin is noticeably lyre-shaped with long filaments.

Diet & Compatibility:

• Diet: This fish is a dedicated Omnivore / Planktivore. Their natural diet consists of suspended zooplankton, algae, and small benthic invertebrates.
• Feeding: Due to their fast metabolism, they require frequent feedings, ideally 3 to 4 times per day. Offer a varied diet of high-quality foods, including frozen Mysis shrimp, spirulina, enriched brine shrimp, marine pellets, and fresh sheet algae (Nori) clipped to the rock.
• Reef Compatibility: It is considered Reef Safe. Genicanthus species rarely nip at or damage stony or soft corals. They may occasionally sample the base of large-polyp stony (LPS) corals, but serious damage is unusual. They are safe with most ornamental shrimp and other invertebrates.
• Temperament: It is Peaceful. The Watanabei Angelfish is generally non-aggressive toward non-conspecific tankmates. They should be kept with other peaceful to moderately aggressive fish. Males may be aggressive toward other Genicanthus males, but a single male can be kept with multiple females (a harem).
• Tank Requirements: Requires a minimum 120-gallon tank due to their adult size (up to 8 inches) and need for extensive open swimming space. They need pristine water quality and plenty of stable rockwork for hiding when stressed.

Quick Facts

• Scientific Name: Genicanthus watanabei
• Primary Common Name: Watanabei Angelfish
• Other Common Names: Blueface Angelfish, Lyretail Angelfish, Black-edged Angelfish, Black-line Angelfish
• Origin: Western Pacific (Fiji, Tonga, New Caledonia, Japan)
• Max Size: Up to 8 inches (20 cm)
• Temperament: Peaceful (Active, mid-water swimmer)
• Diet: Omnivore / Planktivore (Requires frequent feeding)
• Minimum Tank Size: 120 Gallons
• Reef Compatibility: Yes (Excellent choice for a reef tank)