Trachyphyllia Open Brain Coral Care Guide: Sand Bed Placement
The trachyphyllia open brain (Trachyphyllia geoffroyi) is the most photogenic LPS coral in the hobby — a single fleshy polyp that inflates over its skeleton to two or three times its base diameter, glowing in psychedelic rainbow patterns under reef LEDs. They are sand-bed corals from soft-sediment lagoons, which means proper placement is the make-or-break decision. This guide from Gensou Aquascaping at 5 Everton Park covers placement, feeding response and the rainbow morph market.
Identification
Trachyphyllia geoffroyi is a free-living solitary polyp on a small skeletal base. Colours range from solid green or red through complex rainbow morphs combining green, red, purple and orange concentric rings. The closely related Wellsophyllia radiata (often called just “wellso brain”) was historically classified separately but is now considered the same genus — same care profile.
Sand Bed Placement
Trachyphyllia must sit on the sand, not on rockwork. Their skeletal base is smooth and conical, designed to nestle into soft sediment. Placing them on rockwork causes tissue abrasion within weeks. Settle the coral so the base sits in a small depression with the fleshy polyp able to inflate freely without contacting nearby rocks. Maintain at least 10 cm clearance from any aggressive neighbours.
Lighting Tier and PAR
Low to medium light. Target PAR 50-150 µmol at the polyp surface. Too much light causes tissue retraction and bleaching within weeks. Most reef LED tanks deliver appropriate PAR at the sand bed without specific dialling, but verify with a PAR meter if your fixture runs at high intensity. They are perfect for nano reefs with modest LED output. Reef LED units, par meters and acclimation shades sit in the aquarium equipment range.
Flow Requirements
Low and indirect flow. Trachys evolved in calm soft-sediment lagoons and stress under direct flow. The fleshy polyp should gently sway, never billow or fold backward. Place them away from wavemaker outputs and protein skimmer return zones. Sand stirring from nearby sand-sifting fish (diamond watchman gobies) can also irritate them — pick one or the other.
Feeding Response
Strong feeding response. Trachys extend feeder tentacles within minutes of detecting amino acids in the water. Spot-feed with frozen mysis, krill, cyclops or pellet-grade coral food once or twice weekly during the dim evening hours. Direct food onto the polyp with a turkey baster — they eat aggressively and grow noticeably faster when fed regularly. Monthly fed colonies expand 30-50 per cent more than unfed colonies.
Aggression Profile
Low aggression. They produce mild sweeper tentacles only at night and only against direct neighbours. They are themselves stung by hammers, frogspawn, torches and chalices, so position them well away from those species. Other sand-bed corals (rock flower anemones, fungia plates) coexist peacefully at 10+ cm spacing.
Water Parameters
Standard reef parameters: 25-26°C, salinity 1.025, pH 8.1-8.4, alkalinity 8-9 dKH, calcium 420-450 ppm, magnesium 1300-1380 ppm, nitrate 2-10 ppm, phosphate 0.03-0.08 ppm. They are sensitive to alkalinity swings — a 1 dKH change within 24 hours can trigger tissue recession. RODI is mandatory; salt mix, refractometer and ATO units sit in the marine saltwater range.
Common Issues
Tissue recession away from the skeleton edge usually points to flow or light excess. Brown jelly disease can hit underfed or stressed specimens — iodine dip and removal of necrotic tissue is the standard response. Sand grain abrasion at the base causes white skeleton patches that should be inspected during weekly maintenance.
Rainbow Morph Sourcing
Premium colour morphs command serious prices in Singapore. Standard solid greens or reds run SGD 80-150 from Iwarna and Aquamarin. Two-tone specimens range SGD 200-400. True rainbow morphs with multi-colour concentric rings reach SGD 600-1500 for collector-grade pieces. Carousell coral traders sometimes have aquacultured frags at lower prices. RDC Reef Discus Centre stocks them irregularly.
Long Term Care
Healthy trachys live for decades when placed correctly and fed regularly. They grow slowly compared to candy canes but the fleshy polyp can expand to 25 cm diameter on a 10 cm skeleton over five to seven years. They become showpiece corals in mature reefs, often photographed and shared as the centerpiece of a sand-bed garden display.
Related Reading
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