Moorish Idol

Species overview

The Moorish Idol (Zanclus cornutus) is an iconic marine fish with a tall, disc-shaped body, bold black, white and yellow bands, and a long, trailing filament on the dorsal fin.

It is one of the most difficult reef fish to keep, and suits only experienced keepers with large, mature tanks.

Quick facts

• Scientific name: Zanclus cornutus
• Care level: Expert only. Extremely challenging.
• Adult size: 18–23 cm
• Minimum tank: 470–750 L or more
• Temperament: Peaceful to semi-aggressive
• Reef safe: With caution
• Diet: Omnivore, specialised sponge feeder

Water and system compatibility

• Water: Marine and reef.
• Temperature: 22–26°C
• pH: 8.1–8.4
• Specific gravity: 1.020–1.025

Need to work out your tank's litreage? Use our volume calculator.

Tank set-up

• Flow: Moderate to high.
• Aquascape: Plenty of open swimming space, plus rockwork and caves for hiding.

Feeding

Moorish Idols are well known for refusing food in captivity. They need live rock rich in sponges and macroalgae. Once settled, offer sponge-based frozen foods, spirulina, finely chopped clam, mysis and quality pellets.

Temperament and tankmates

• Corals: May nip stony corals (LPS and SPS), clams and polyps, especially if underfed.
• Other fish: Usually peaceful with peaceful tankmates. Can be aggressive towards similar-looking fish or other Moorish Idols, unless kept as a bonded pair in a very large tank.

Acclimatisation

Moorish Idols are very delicate and stress badly during shipping. Many carry internal parasites or refuse all food.

A hardier alternative: Schooling Bannerfish

Because Moorish Idols are so hard to keep long term, many aquarists choose the Schooling Bannerfish (Heniochus diphreutes) instead. It has very similar black, white and yellow colouring and a long dorsal filament, but it is much hardier, easier to feed and far better suited to home aquariums.