Swallowtail Angelfish

Swallowtail angelfish, also known as the Japanese swallowtail angelfish, are a beautiful and highly sought-after species of marine fish. With their striking appearance and unique behaviors, these fish have become a popular choice for aquarium enthusiasts around the world.

In this blog post, we will take a closer look at swallowtail angelfish, including their physical characteristics, natural habitat, dietary requirements, and behavior. We will also discuss the best ways to care for these fish in a home aquarium, including tank setup, water parameters, and suitable tank mates.

Category Information
Lifespan 7-10 years
Temperature 72-78°F (22-26°C)
Min size 70 gallons
Max size Up to 8 inches (20 cm)
Species Genicanthus spp.
Family Pomacanthidae
Scientific Name Genicanthus spp.
Origin Indo-Pacific region
Diet & Nutrition Omnivorous, feed a varied diet of meaty foods, algae, and pellets
Breeding Difficult to breed in captivity
Tank mates Peaceful community fish, avoid other angelfish
Tank size Minimum 70 gallons, larger for adult specimens
Average price $60-$200 USD

Physical Characteristics

Swallowtail angelfish are known for their distinctive appearance, with a body that is primarily black with bright yellow markings on their fins and tail. They have a long, pointed snout and sharp teeth, which they use to feed on small invertebrates and other prey. These fish can grow up to 6 inches in length, and their striking coloration makes them a standout addition to any aquarium.

Natural Habitat

Swallowtail angelfish are native to the Western Pacific Ocean, where they can be found in the waters surrounding Japan, Taiwan, and the Philippines. They typically inhabit coral reefs and rocky areas, where they can find plenty of small invertebrates to feed on. In the wild, swallowtail angelfish are known for their territorial behavior, and they will defend their territory aggressively against other fish that come too close.

Dietary Requirements

In the wild, swallowtail angelfish feed on a variety of small invertebrates, including crustaceans, worms, and mollusks. In a home aquarium, it is important to provide these fish with a varied diet that includes a mix of high-quality pellets, frozen or live foods, and fresh vegetables. They should be fed two to three times per day, with portions that are small enough to be consumed in a few minutes.


Swallowtail angelfish are known for their territorial behavior and can be aggressive toward other fish that invade their space. They are best kept in a species-only tank or with other non-aggressive fish that are of a similar size and temperament. These fish are generally hardy and easy to care for, but they can be sensitive to changes in water parameters, so it is important to maintain a stable and consistent environment.

Tank Setup

When setting up a tank for swallowtail angelfish, it is important to provide plenty of hiding places and areas for the fish to establish their territory. A minimum tank size of 75 gallons is recommended, and the tank should be equipped with a high-quality filtration system and a protein skimmer to maintain optimal water quality. Live rock and a sand substrate can help to create a naturalistic environment, and a few carefully selected corals can provide additional visual interest.

Water Parameters

Swallowtail angelfish require stable water parameters to thrive, with a temperature range of 72-78 degrees Fahrenheit and a pH range of 8.1-8.4. Salinity should be maintained at a specific gravity of 1.020-1.025, and regular water changes are essential to maintain good water quality. It is also important to monitor levels of ammonia, nitrite, and nitrate, and to adjust filtration and feeding accordingly to prevent spikes in these levels.

Suitable Tank Mates

Swallowtail angelfish are best kept in a species-only tank or with other non-aggressive fish that are of a similar size and temperament. Suitable tank mates may include other types of angelfish, tangs, and small to medium-sized reef-safe fish. However, it is important to avoid keeping swallowtail angelfish with aggressive or territorial fish, as this can lead to stress, injury, or death.


Can swallowtail angelfish change gender in captivity?

While swallowtail angelfish and other species of angelfish are known to change gender in the wild, it is rare for them to do so in captivity. This is because the social dynamics and environmental conditions are typically more stable in an aquarium than in the wild, which means there is less pressure on the fish to change gender.

Is gender change in swallowtail angelfish harmful?

No, gender change is a natural process for swallowtail angelfish and is not harmful to their health or well-being. It is a natural adaptation that helps the fish survive and reproduce in the wild. However, in captivity, it is not necessary for their survival and is unlikely to occur

How can you tell the gender of a swallowtail angelfish?

In juvenile swallowtail angelfish, it can be difficult to determine their gender. However, as they mature, males will develop a longer, pointed anal fin, while females will have a more rounded anal fin. Additionally, males may exhibit more vibrant coloration than females.

In conclusion, Swallowtail Angelfish is a beautiful and unique fish that requires a suitable environment and a varied diet to thrive. While they can be challenging to breed in an aquarium setting, they are relatively hardy and can be kept with other non-aggressive species. With proper care and attention, Swallowtail Angelfish can be a fascinating addition to any aquarium

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