Swallowtail Angelfish Profile

Genicanthus melanospilos

Swallowtail angelfish (Genicanthus sp.), front view
Dorling Kindersley/Dorling Kindersley/Getty Images

Scientific Name: Genicanthus melanospilos (Bleeker, 1857).


Other Common Names: Japanese Swallowtail, Blackspot, Blackspot Lyretail, Spotbreast, and Zebra Angelfish.


Western Indo-Pacific, Australia.

Average Size:

Medium category species that grows to 7 inches.


An extremely active species that should be provided lots of room for swimming around.

Minimum Tank Size Suggested:

100 gallons.

Sexual Identification 

This is one of a few angelfishes that can easily be identified by sex as male or female, because of their differences in appearance. The male is marked with thin, dark vertical bands that cover the body from the head to where the dorsal and anal fins end, followed by a yellow banded area at the base of the tail, and thus named a Zebra Angelfish.

Characteristics and Compatibility

Often a difficult shipper, but if a healthy specimen is obtained, it settles into aquarium life rather quickly. Males will fight with same as well as other Genicanthus genus males, especially ones similar in coloration. Can be kept singly, as a pair or a small group of females can be housed with one male in larger aquariums. Not overly aggressive, but may chase after small peaceful planktivores. Typically ignores other fish species including non-related angelfishes.


Naturally a planktivore, this is an angelfish that often browses on diatom and filamentous algae in aquariums.

Should be fed a varied diet of meaty fares and marine algae-based foods, such as finely chopped fresh shrimp and frozen silversides, frozen brine and mysis shrimp and angelfish preparations, dried seaweed (nori), enriched flakes or pellets containing Spirulina.

An Interesting Feeding Trait

This fish will gulp food from the water's surface, which makes it swallow air at the same time.

It is not unusual for the fish to become bloated, resulting in the fish appearing to be struggling while swimming head down, but don't worry. The fish gets rid of this trapped air by expelling bubbles from its mouth and anus. In other words, it burps and farts, which is funny to watch as the Hippo Tang in our aquarium shadows the angel, trying to eat the bubbles thinking its food.

Care Rating

Our recommended care rating for this angelfish—intermediate level for healthy specimens that are already eating well, but require experienced level if stressed and not yet adapted to aquarium life.