Zoanthid Care Guide (Zoas)

Zoanthids, or zoas, are colonies of small button polyps that come in almost every colour imaginable. They are hardy, grow steadily, and collecting different colour morphs is half the fun.

Light and flow

Low to medium light suits most zoas, and they colour up well under it. Too much light too quickly makes them stay closed, so start them lower and move them up if they look happy. Gentle to moderate flow keeps them clean without blasting the polyps shut.

Placement

Low to mid rockwork. They spread across the rock over time, so leave a little space around a colony. They are peaceful, but keep them away from corals with long sweeper tentacles like Hammers and Torches.

Feeding

Zoas get most of what they need from light. A finely powdered coral food now and then is optional.

Handling them safely: palytoxin

Some zoanthids contain palytoxin, a strong toxin. It is safe to keep them, but handle them with care: wear gloves and eye protection when you touch or frag them, never cut them while they are under running water or where water can splash, never boil or scrub rock they have grown on, and wash your hands afterwards. If you get tank water in your eyes or feel unwell after handling them, get medical advice and say you were handling zoanthids.

Common problems

• Staying closed: often a change in light, a pest, or a parameter swing. Check alkalinity first.
• Melting away: can be pests like zoa-eating nudibranchs or spiders. Dipping new colonies helps prevent this.
• Long, stretched stalks: usually not enough light.