RecifAtHome guide
Zoanthus are among the easiest and most colourful corals to keep. We grow thousands at our coral aquaculture facility in Roche-lez-Beaupré, France: here is our advice for keeping them successfully, along with the precautions you need to know.
In short
- Easy corals, ideal for beginners, available in countless colours.
- Moderate light (100 to 250 µmol/m²/s PAR) and medium flow.
- They prefer water that is not completely stripped of nitrate and phosphate.
- They can contain palytoxin: wear gloves and eye protection when handling them.
Zoanthus or Palythoa?
Zoanthus are small colonial polyps connected by a shared base. Palythoa are larger, often with a duller oral disc, and generally contain more palytoxin. Trade names ("Utter Chaos", "Rasta", "Fruit Loops"…) refer to colour morphs, not species.
Our Zoanthus: aquacultured and maricultured
- Zoanthus ultra aquaculture RAH are grown in aquariums at our facility: they are accustomed to aquarium conditions from the outset.
- Acclimated mariculture Zoanthus are farmed in the sea and then acclimated at our facility for several weeks before sale.
Lighting, flow and placement
Zoanthus adapt to a wide range of lighting. Aim for 100 to 250 µmol/m²/s PAR: too much light too quickly makes them close, while too little makes them stretch and lose colour. Place a new frag halfway up the tank and move it if needed. Moderate, alternating flow prevents debris from settling on the polyps.
Parameters and feeding
Zoanthus tolerate a wide range of parameters but prefer stability. Water that is too nutrient-poor (nitrate near 0, undetectable phosphate) makes them shrink and fade: maintain around 2 to 10 mg/L nitrate and 0.03 to 0.1 mg/L phosphate. They benefit from fine coral food once or twice a week, though it is not essential.
Fragging
A colony is easy to frag: cut the tissue between polyps with a blade or side cutters, then attach the frag to a plug with cyanoacrylate gel glue. Keep time out of water as short as possible and follow the precautions below.
Palytoxin: essential precautions
Palytoxin is a very potent toxin found in some Zoanthus and especially in Palythoa. Accidents are rare but serious: skin and eye irritation, fever, breathing difficulties.
- Wear gloves and safety glasses when handling or fragging.
- Never scrub, scrape or clean a polyp-covered rock out of water, and never pressure-wash it or put it in boiling water: the toxin can become aerosolised or airborne.
- Cover any cuts on your hands and wash thoroughly after handling.
- In case of eye contact or feeling unwell, see a doctor or call a poison centre, mentioning "palytoxin".
Good to know
These precautions are not meant to scare you: they are simple, and thousands of hobbyists keep Zoanthus without any incident.
Pests and problems
- Zoanthid-eating nudibranchs: small, often matching the colour of the polyps and hiding at their base.
- Sea spiders (pycnogonids): tiny pests that pierce the polyps.
- Polyps staying closed: check lighting, salinity, a recent alkalinity swing or a fish nipping at them.
A dip in a suitable product (coral treatments) on arrival removes most pests, though not always their eggs: keep an eye on new colonies for a few weeks. Our colonies are checked before shipping.
Frequently asked questions
Are Zoanthus easy to keep?
Yes. They are among the easiest corals and perfect for beginners, as long as water is stable and lighting moderate.
Are Zoanthus dangerous?
Some contain palytoxin. Wearing gloves and eye protection and never scraping a rock out of water keeps the risk very low.
Why are my Zoanthus closed?
Usually a sudden lighting change, pests (nudibranchs, sea spiders), a fish nipping at them or unstable parameters.
How much does a Zoanthus frag cost?
In our range, Zoanthus frags start at around €15, with rare morphs reaching €200.
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Guide written by the RecifAtHome team, coral aquaculture in Roche-lez-Beaupré (France) since 2010. Updated: October 2026.