Koran Angelfish

Pomacanthus semicirculatus

Also known as Semicircle Angelfish, Blue Koran Angelfish

SaltwaterFish

Koran Angelfish (Pomacanthus semicirculatus) — Stan Shebs · CC BY-SA 3.0

Care at a glance

Temperature: 73–81°F (23–27°C)
pH: 8.1–8.4
Adult size: 15.7 in (40 cm)
Minimum tank: 132 gal (500 L)
Temperament: Mostly peaceful
Social behavior: Solitary
Swim level: Middle
Difficulty: Difficult
Breeding: Hard
Rarity: Common
Reef safe: Not reef safe
Origin: Indo-Pacific, from the Red Sea and East Africa to Samoa, north to southern Japan and south to Western Australia
Family: Pomacanthidae

Overview

Koran angelfish are semi-aggressive, mainly toward other angelfish and similarly shaped fish, so plan on keeping just one unless the tank is very large. They graze sponges, tunicates, and algae in the wild, so offer nori and other marine algae alongside frozen meaty foods like mysis and brine shrimp. They are not reef safe: expect them to nip at soft and stony coral polyps and clam mantles if kept around them.

In the wild

Koran angelfish range across a huge stretch of the Indo-Pacific, from the Red Sea and East Africa to Samoa, living on reef flats, lagoons, and outer slopes from the surface down to about 40 meters. They stay close to shelter, ducking into rock and coral cover when startled. A tank needs mature, extensive rockwork with caves and established algae growth to match the grazing and hiding they would do in the wild.

Good to know

Pomacanthus semicirculatus reaches about 40 cm and can live two decades or more in good care. The juvenile is dark blue black with concentric white and pale blue swirling rings, the 'semicircle' pattern the scientific name refers to, while the adult turns olive green to blue grey with fine scale markings, a pale blue mouth, and a dark comma-shaped mark ringed in blue behind the gill cover. The two color phases look so different that early collectors sometimes sold them as separate species.

Did you know

This is one of the few large angelfish to have had its natural spawning, eggs, and larvae documented under research aquarium conditions, a 2009 study that gave scientists a rare look at how a Pomacanthus angel actually breeds.