30.09.2026

Trachyphyllia, Acanthophyllia and Cynarina: Placement and Care

Trachyphyllia, Acanthophyllia and Cynarina stand out in a reef aquarium: large fleshy polyps, vivid colours and a distinctive shape in every specimen. That soft tissue needs a carefully chosen position. Instead of aiming for a single “perfect” PAR value, watch how your particular coral responds to light, flow and its neighbours.

What these three corals have in common

All three are sold as large-polyp stony corals (LPS). Their expanded polyps may inflate considerably during the day and shrink again later. That alone does not indicate disease. A stable aquarium, a protected position and enough room for the tissue to expand fully matter most. An individual specimen's needs can differ from broad advice about its genus.

When choosing a coral, inspect its photographs closely. Is the tissue intact throughout? Are there injuries around the edge or on the skeleton? The product photographs of our WYSIWYG corals show the actual specimen offered. You can also browse our current Trachyphyllia, Acanthophyllia and Cynarina.

Placement: a gentle surface and room to expand

An open spot low in the reef or on the sand bed is often a good starting point. Make sure no sharp rock edge presses against the inflated tissue. The coral should sit securely and not topple when the pumps run. Under a strong LED, start in a less brightly lit position and move it only gradually. A newly introduced specimen needs time before you can judge its normal expansion.

Choose gentle, indirect flow. Water should move past the coral without constantly pushing its tissue sideways or blowing sand onto it. If a polyp is persistently distorted on one side, check the pump's direction first. Leave space from neighbouring corals, too: expanded LPS may touch or sting them. Judge the distance with the polyp open, not just by the small skeleton.

Stable water parameters matter more than rapid adjustments

Keep temperature, salinity and alkalinity as steady as possible within your aquarium’s established range. Calcium and carbonate availability matter for skeletal growth. Monitor magnesium as part of the seawater chemistry too. Track the readings and avoid changing several things at once. Our guide to stable alkalinity helps with this. Do not subject a newly delivered coral to an abrupt change just to move one number into a supposedly ideal range.

Feeding without polluting the water

These corals gain much of their energy from their symbiotic algae and can also take suitable food. Occasionally offer a healthy, settled coral a small portion it can actually grasp. Place the food gently on an open polyp; do not push it into the mouth. Remove food that remains uneaten or is spat back out. A larger portion is not automatically better. Our LPS feeding guide walks through the process.

If the coral does not open

A coral may initially look smaller after shipping and introduction. First check for excessive light or flow, sand on the tissue and contact with another coral. Compare temperature, salinity and your most recent water test results. Avoid moving the coral again every day; otherwise it is hard to tell whether a change helped. Our post-shipping acclimation guide can help you get started.

Visible tissue injury, continuing tissue loss or an unusual smell are different from a temporarily shrunken polyp. Document the change under neutral light and seek advice promptly. For a newly delivered coral, also see our arrival guidance.

Frequently asked questions

How much light do these corals need?

Start in a sheltered position under relatively low to moderate light. The actual intensity depends on your lamp, tank depth and the coral's previous conditions. Increase light slowly and watch the animal's response.

Do they always need to sit on the sand bed?

A secure position that protects the tissue is what matters. An open place low in the reef can also work if sharp edges and neighbouring corals cannot touch the tissue.