Zoanthids: Why Colour Morphs Vary and How to Place Them Safely in Your Reef

Zoanthids are one of the easiest corals to fall in love with because a single colony can carry a dozen tiny suns worth of colour, and every grower seems to have their own name for a slightly different combination. If you have ever wondered why one tank's 'Rainbow' looks nothing like another's, or why frags labelled 'Utter Chaos' or 'Lunar Eclipse' command so much attention on a swap thread, this profile covers the naming quirks, the actual husbandry, and how to bring new frags into your system without losing them to pox or melt.

Why do zoanthid names vary so much?

Zoanthid taxonomy is messy. Most of what we call zoas in the hobby belong to a handful of genera, commonly Zoanthus and Palythoa, but hobby names like 'Everlasting Gobstopper', 'Lunar Eclipse', 'Utter Chaos' and 'Pink Zipper' are not scientific descriptions. They are trade names given by growers to describe a specific colour combination, often a coloured skirt around a contrasting mouth or centre. Because zoas can shift colour slightly depending on lighting spectrum, feeding, and even the individual polyp's position in a cluster, the same genetic line can look different in two tanks. That is why photos under actinic-heavy lighting often look more saturated than the same coral under daylight-only globes. When you buy a named morph, you are buying a specific genetic lineage that a grower has propagated and tagged, not a guaranteed universal look.

Light and flow requirements

Zoanthids are generally considered a moderate-light coral, which makes them forgiving for people running mixed reef tanks with LPS, softies and the odd SPS colony. Aim for somewhere in the 50 to 150 PAR range depending on the specific morph. Deeper colour morphs and Palythoa-type polyps often do well lower in the tank or under shaded rockwork, while brighter Zoanthus lines can handle a spot closer to the light source without bleaching out. If you are running LED fixtures, start new colonies at a lower intensity and lower position, then nudge them up over two to three weeks and watch how the polyps respond.

Flow should be gentle to moderate. Zoas do not like being blasted directly by a wavemaker, and strong laminar flow can keep polyps closed for long stretches, which starves them of feeding opportunity and light exposure. A soft, indirect flow that ripples the polyps without flattening them is the target. Placing colonies on rock ledges or in slight depressions out of the main flow line usually works well.

Feeding and water parameters

• Target temperature: 24 to 26°C
• Salinity: 1.025 to 1.026
• Alkalinity: stable, ideally 7 to 9 dKH with minimal swing
• Feeding: broadcast feed with fine particulate coral food or phytoplankton a few times a week, though many zoas thrive largely on light and dissolved nutrients

Acclimatising new frags without triggering pox or melt

Zoanthid pox and rapid tissue melt are the two things that catch people out with new frags, and both are largely preventable with a slow, deliberate introduction.

• Dip new frags in a coral-safe iodine or povidone-based dip before they enter your system, and rinse briefly in clean saltwater afterwards.
• Quarantine for at least two weeks if you can. Zoa pox is thought to be viral or bacterial and can spread through direct contact or shared water, so isolating new arrivals protects your existing colonies.
• Avoid sudden parameter swings. A frag shipped overnight has usually sat in a bag with falling pH and rising ammonia, so acclimatise slowly by drip or float method over 20 to 30 minutes rather than dumping it straight in.
• Introduce to low, indirect flow and moderate light for the first week, even if the target spot is brighter. A stressed frag that has not opened yet can bleach quickly under strong light.
• Watch daily for the first fortnight. Polyps that stay closed for more than a few days, or develop white lesions at the base, should be isolated again and dipped a second time.

Zoanthids reward patience more than any other coral in a mixed reef. A colony that seems to sulk for two weeks after arrival will often carpet a rock within a few months once it settles, and named morphs like the ones mentioned above are prized precisely because a well-established cluster becomes a genuine centrepiece. Because named morphs move in and out of our lists as growers cycle frags through, check out our stock list for zoanthids to see what is currently being propagated, and pair a new addition with a bottle from our dosing pumps range if you are chasing more stable alkalinity, or a fine coral food from our coral food range to encourage faster polyp extension once your new frag has settled in.