Care
The Masked Swallowtail Angelfish is known from the seaward rocky and coral reefs of southern Japan to Taiwan and northern Philippines, to depths of 100m (328ft). These graceful fish are protogynous hermaphrodites and form harems consisting of one male and several smaller females. Here they may be observed in their little groups, feeding on plankton in the water column. The angelfish from the genus
Genicanthus are unusual in that they are not classed as true dwarf angels, yet they remain relatively small sized fish. They also display a remarkable sexual dimorphism. This particular species is ideal for the deepwater reef aquarium with lots of shady overhangs and crevices amongst the live rock. Although it does not grow to a huge size, the Masked Swallowtail Angelfish is a very active species that does require a good amount of space. Keep either singly, as a male-female pair, or one male with a harem of several females, but never house a male
G. semifasciatus with another male or with any other members of the
Genicanthus genus - especially those of similar appearance. Will usually ignore some of the more placid species of dwarf angelfish from the
Centropyge genus, but as each fish is an individual and behaviour is certainly not set in stone, do observe very carefully. These fish have been known to pick on small planktivores such as wreckfish (
Pseudanthias spp.), fairy and flasher wrasses, and fire fish, but they are perfectly safe with soft and stony corals. Good water movement is essential, and plenty of live rock will be appreciated for shelter/grazing (plenty of dimly lit areas will also help with the settling in period). Masked Swallowtail Angelfish generally adapt very well to life in captivity, accepting aquarium fare and acclimatising to the conditions found in a well-maintained tank. This species is recommended for intermediate to advanced aquarists only. They typically command a fairly high price because of the difficulty in collecting fish from deeper waters. May also be seen on sale as Japanese Masked Swallowtail Angelfish or Japanese Swallowtail Angelfish.
Feeding
Should be offered a varied diet including Spirulina & marine algae as well as meaty fare such as vitamin/Spirulina-enriched brineshrimp, Mysis shrimp, special sponge-based Angelfish preparations, and finely chopped krill/squid/cockle/mussel. Feed small amounts 3 times per day.
Breeding
This species has not been bred in the home aquarium.
