Rainbow Trachyphyllia (Trachyphyllia geoffroyi) Propagation Guide
Why the rainbow morph of Trachyphyllia geoffroyi is not routinely fragged: a free-living solitary polyp that reproduces sexually on the reef rather than by conventional fragmentation.
Overview
The rainbow Trachyphyllia is a high-color form of Trachyphyllia geoffroyi, a large-polyped stony coral in the family Merulinidae prized for concentric rings of red, green, blue, and gold. Like all open brains it is a free-living coral that sits unattached on the sandbed, inflating a very fleshy mantle by day. The color morph does not change its biology: it is the same solitary, flabello-meandroid polyp.
Reproductive Mode
The rainbow Trachyphyllia is essentially a single free-living polyp and is not suited to conventional fragging. Reef Builders places single-polyp LPS such as scolys, meat corals, and fungias outside conventional fragging techniques, and the open brain falls into the same group, so it is not routinely fragmented to multiply the rainbow color.
Fragging / Asexual Propagation
- Branch-separation fragging does not apply, since there are no heads on branches to divide.
- Asexual increase is mainly through slow natural budding of the polyp, not deliberate cutting.
- Cutting through the single polyp to multiply the rainbow morph is uncommon, risky, and considered advanced.
- In practice, the rainbow color is propagated by buying additional wild or aquacultured specimens rather than by fragging.
Because the prized rainbow pattern lives on one continuous polyp, dividing it would require cutting through the colored tissue, which can be fatal and is therefore avoided by most keepers.
Conditions for Propagation
Keep temperature near 24-26 degrees Celsius and pH 8.1-8.4 with stable alkalinity, calcium, and magnesium. The coral rests on the sandbed in low flow and medium light; stable conditions and spot feeding preserve color and support recovery if a polyp is ever divided.
Sexual Reproduction
On the reef, Trachyphyllia geoffroyi reproduces sexually. The species is heavily collected for the trade and is listed by the IUCN as Near Threatened, which means most rainbow specimens originate from wild collection rather than from in-tank propagation.
Common Challenges
The fleshy mantle is easily torn by sharp rock or strong flow, and damage can spread as infection. Because the coral is not readily fraggable, attempting to divide a colored polyp risks losing the whole specimen, so propagation of the rainbow morph is not recommended in normal aquarium care.