Open Brain Coral Care Guide
Open Brain Coral (Trachyphyllia geoffroyi) is a LPS coral. Care covers 50-150 PAR, low flow, reef parameters and feeding; intermediate level.
Compiled by Aquairi from published sources · Published · Updated
Overview
Open Brain Coral (Trachyphyllia geoffroyi) is a LPS coral in the family Merulinidae. Free-living LPS that sits on sandbed; inflates a fleshy mantle by day. Wide color range from green to red and rainbow.
Taxonomy
- Family: Merulinidae
- Genus: Trachyphyllia
- Scientific name: Trachyphyllia geoffroyi
- Common synonyms: Trachy, Folded Brain
Habitat
In the wild, Trachyphyllia geoffroyi is reported from Indo-Pacific, Australia, where it occupies mid to lower reef slopes and lagoons (typically 5-30 m). The species adopts a massive growth form on hard substrate within zooxanthellate reef communities.
Tank requirements
- Salinity (specific gravity): 1.024-1.026
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- Carbonate hardness (dKH): 8-11
- Calcium: 400-450 ppm
- Magnesium: 1280-1350 ppm
- Phosphate (max): 0.03 ppm
- Nitrate (max): 5 ppm
- Minimum system age: 6 months
Placement and lighting
- PAR (placement zone): 50-150 PAR
- Water flow: low
Mount this LPS coral on the lower or mid rockwork or on the sand bed (for free-living forms) where light is moderate. Strong direct flow can damage the fleshy tissue; aim for indirect, varied movement.
Feeding
Trachyphyllia geoffroyi hosts symbiotic zooxanthellae and derives most of its energy through photosynthesis. Supplemental target feeding accelerates growth and supports colouration; commonly accepted items include mysis, brine, reef-roids, amino-acids. Feed once or twice per week after lights-out, when polyps are extended.
Compatibility
This coral is moderately aggressive toward neighbours. It extends sweeper tentacles capable of stinging adjacent corals, so leave generous spacing (10-20 cm) between colonies. Reef-safe with most fish and invertebrates.
Care notes
Difficulty level: intermediate. Reported skeletal growth in well-tuned reef tanks is approximately 0.1-0.3 cm/month. Propagation by fragmentation is straightforward for massive colonies — separate branches or polyps with a bone cutter, glue to plug, allow 1-2 weeks for healing. Maintain stable alkalinity (avoid swings above ±0.5 dKH per day) to preserve tissue health.
Open Brain Coral (Trachyphyllia geoffroyi) Propagation Guide
Overview
Trachyphyllia geoffroyi, the open brain coral, is a large-polyped stony coral in the family Merulinidae. It is a free-living species that sits unattached on sandy substrates, sandy reef slopes, and lagoons across the Indo-Pacific, and inflates a very fleshy mantle by day that extends beyond the skeleton and retracts when disturbed. It rarely exceeds about 20 cm in diameter and grows in a flabello-meandroid form.
Reproductive Mode
Unlike branching LPS, the open brain is essentially a single, free-living polyp (sometimes with a few mouths in the valley region) and is not suited to conventional fragging. Reef Builders groups single-polyp LPS such as scolys, meat corals, and fungias as corals that are not conducive to conventional fragging techniques; the open brain belongs to the same category, so it is not routinely fragmented.
Fragging / Asexual Propagation
- Conventional branch-separation fragging does not apply, because there are no separate heads on branches to divide.
- Asexual increase occurs mainly through natural budding of the polyp over time, not deliberate cutting.
- Cutting through the single fleshy polyp is possible but uncommon and risky, and is treated as an advanced technique rather than standard practice.
- For most aquarists, the practical approach is to keep the coral healthy rather than to propagate it.
Because each specimen is one large polyp, dividing it means cutting through living tissue and the skeleton together, which is far riskier than separating branches on a phaceloid coral.
Conditions for Propagation
Keep temperature near 24-26 degrees Celsius and pH 8.1-8.4 with stable alkalinity, calcium, and magnesium. The coral sits on the sandbed in low flow and medium light; gentle handling and spot feeding support recovery if a polyp is ever divided.
Sexual Reproduction
On the reef, Trachyphyllia geoffroyi reproduces sexually. The genus is heavily collected for the aquarium trade, with over 60,000 specimens reported exported from Indonesia in 2005, and the IUCN lists it as Near Threatened, underscoring that wild collection rather than captive propagation supplies most specimens.
Common Challenges
The fleshy mantle is easily damaged by sharp rock or strong flow and can tear, opening the door to infection. Because the coral is not readily fraggable, attempts to divide a single polyp risk losing the whole animal, so propagation is not recommended for typical aquarium keeping.