Masked Swallowtail Angelfish (Japan)

The Masked Swallowtail Angelfish (Genicanthus semifasciatus) is a peaceful species that is reef-safe, admired for its striking sexual dimorphism, swallowtail-shaped fins, and graceful swimming patterns.

Males typically display vivid horizontal black striping across a pale body, with long trailing swallowtail extensions and bold coloration, while females/juveniles are more subdued, usually pale yellow to white with minimal markings, lacking the bold stripes of males.

They reach about 7 inches in adult size and should be housed in aquariums of at least 125 gallons. Provide ample open swimming space, live rock for grazing and shelter, and hiding spots, along with stable water parameters (salinity ~1.020–1.025, temperature ~72–79°F, pH ~8.1–8.4). A secure lid is recommended since these angelfish are known jumpers.

Diet should consist of mysis shrimp, brine shrimp, copepods, enriched frozen foods, high-quality marine pellets, and some algae-based offerings. With proper care, the Masked Swallowtail Angelfish makes a standout addition to larger reef or community aquariums, admired for both its beauty and relatively peaceful temperament.

International Aquatics Quarantine & Guarantee: All fish are checked by marine vets, given a formalin bath, and held for 14 days in copper-treated systems. We feed Selcon-soaked food with Kanaplex and Metroplex during quarantine. Unless marked, all livestock comes with our 15-Day Guarantee. You will receive a video of your fish eating before shipment. On request, we also send photos/videos after arrival at IA. Some species are import-to-order (3-10 business days). Many common species are already cleared or near the end of QT.

Several species will be import-to-order and may take anywhere from 3-10 business days to secure. Once your fish is secured, you will be notified, and the quarantine process will then begin.