Swallowtail Angelfish Profile

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


Family: Pomacanthidae

Scientific Name: Genicanthus melanospilos (Bleeker, 1857).

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

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.


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.

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.

Guides 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.

Personal Notes From Your Guides:

Dateline 07/23/2011: In the four years we have had our beautiful female Swallowtail Angelfish in our 92g reef tank it has never bothered any of the different types of soft and stony corals and other sessile invertebrates we have kept in this aquarium. It has been a peaceful and friendly fish, communing well with all its tank mates, which to date includes a Naso Tang, Yellow Tang, Hippo or Pacific Blue Tang, Firefish Goby, and Red Saddleback or Fire Clownfish. We love this angelfish, and have been considered obtaining a mate for her.

Dateline 12/30/07: This angelfish has shown no further signs of interest in the clam, nor any of the corals we have put in the aquarium to date.

Dateline 11/04/07: Everything we have read says the Japanese Swallowtail Angelfish is invertebrate safe, so we got a female as a starter fish for our new 92 gallon reef tank.

However, we saw her nip at a 3 inch T. Crocea clam today. This may have been due to the aquarium being algae free at this stage, and with nothing to pick at this fish was just checking things out, or might have just been going after something drifting by or that had landed on the clam's mantle.

The first two fish in our tank, the Angel and a Yellow Tang, we had been feeding them 2 times a day, but somewhat sparingly as not to pollute the system, which had recently finished cycling. We have slightly increased the amount of foods being offered per feeding (all water parameters are fine since) to see if this will help satisfy this fish's rather voracious appetite, and are keeping a close watch on its behavior around the clam.

~ Debbie and Stan Hauter