Koran Angel

Overview

The Koran Angel (Pomacanthus semicirculatus) — also called the Semicircle or Half-circled Angelfish — is one of the great transformation fish of the hobby. Juveniles are deep blue-to-black, crossed by narrow white and electric-blue semicircular bands that arc across the body like flowing script (the origin of the 'Koran' name). As they mature, that pattern dissolves into an entirely different adult look: an olive-to-yellow-green body densely speckled and edged in sapphire blue, with blue-trimmed fins, trailing filaments and a yellowish tail.

It's a large, intelligent, regal fish that becomes bold and personable, learning to recognise its keeper and cruise its territory with real presence.

Two honest headlines shape how you keep it. First, it's one of the hardier large angels and adapts well to aquarium life, which makes it a good entry point into big angels for an intermediate keeper. Second, it grows large, lives for well over a decade, and is not a coral-tank fish — so it belongs in a spacious fish-only or FOWLR system you're prepared to commit to long term.

Compatibility

Toward non-angelfish the Koran is relatively peaceful — juveniles in particular are shy and reclusive — but it becomes increasingly territorial as it matures, and it's genuinely aggressive toward other angels, especially of its own genus or similar appearance. The rule is one angel per tank, and because it's one of the largest of its group and will claim the tank as its own, it's best added last.

Given a large enough system, it coexists well with other robust, active fish of similar temperament — tangs, larger wrasses, and the like — and even some peaceful species if there's ample space. Avoid other large angels, dwarf angels, and overly aggressive tankmates, and provide plenty of rockwork so everyone has territory and boltholes.

Health & quarantine

For a large angel, the Koran is refreshingly hardy — it adapts readily and usually eats most foods with gusto, which is a big part of why it's considered one of the better big angels to start with. Even so, large angels are prone to ich and other parasites, especially through the stress of collection and introduction, so a proper quarantine period and a slow, drip acclimation are strongly recommended, and a UV steriliser and good protein skimmer are worthwhile support. Juveniles can be a little more delicate and shy, so choose a healthy, actively feeding fish. Keep it in a large, mature system with pristine, well-oxygenated water and robust filtration, and it's a long-term resident — often living 15 to 20 years.