Open Brain Coral

The open brain coral is an LPS that lives freely on the sand and does not attach to rock. Its skeleton is usually hourglass-shaped and carries between one and three mouths. During the day the top of the skeleton is covered by an inflated, fleshy mantle that spills over its edges; when touched, this mantle deflates quickly. At night several rows of tentacles open around the mouth. The mantle can be green, red, blue, yellow or brown in tone.

In the hobby it is called "Trachy". The old name Wellsophyllia radiata is today a synonym of the same species. Colonies that reach the trade are mostly wild-collected, and its trade is subject to CITES Appendix II; if possible, choose a farmed colony, and if it comes from the wild, buy a specimen whose tissue covers the whole skeleton, whose mouth is closed and whose mantle inflates.

• Rainbow Trachy: expensive forms carrying red, green, orange and blue rings together in a single colony.
• Red or pink Trachy: a red-dominant mantle.
• Green Trachy: green with fluorescent tones, the most commonly seen form.

It lives in the Red Sea, the Indian Ocean and the Western Pacific, on sandy and muddy bottoms between reefs, especially around continental islands. In the wild it is found together with other free-living corals; large colonies are seen only in sheltered, shallow bays. It is rare on the reef itself.

• Light: Low to moderate, about 50–150 PAR. A corner on the sand where the light does not hit directly is usually enough.
• Flow: Low and indirect. The mantle should ripple gently; strong flow tears the mantle and prevents it from inflating.
• Placement: It must be placed on the sand, with its pointed base lightly buried. If placed on rock, it can fall and be damaged.
• Water parameters: Salinity 1.024–1.026, KH 7–10 dKH, calcium 400–450 mg/L, magnesium 1250–1350 mg/L. Sensitive to sudden KH and salinity changes. Nitrate 2–10 mg/L and phosphate 0.03–0.1 mg/L are suitable.

Photosynthetic, but it is one of the LPS that need supplementary feeding. Once or twice a week, after the lights are off and the tentacles have opened, mysis, chopped shrimp or an LPS food is released near the mouth. In specimens that go unfed for a long time, the mantle shrinks and the skeleton starts to show.

The tentacles that open at night have stinging cells and reach a few centimeters; they can burn a coral they touch. Keep it about 10 cm away from other corals on the sand. Sand-stirring gobies and sand-sifting sea stars can cover it with sand; if such animals are present, check the coral regularly.

Dwarf angelfish and some large angelfish may pick at the mantle. Hermit crabs can irritate the tissue by walking over the mantle.

It is rarely propagated in the aquarium. Colonies with more than one mouth can be cut between the mouths with a diamond-blade saw, but because the tissue is thick and delicate this is risky; it should only be done on very healthy colonies and with experience. Colonies grow naturally by mouth division. This is why most specimens on the market come from the wild.

• Exposed skeleton: tissue receding from the edges usually comes from starvation, too much light or wounds suffered during shipping.
• Brown jelly and bacterial infection: can start in wounded tissue and spread quickly; if noticed early, the affected specimen is treated with a coral dip in a separate container.
• Mantle not inflating, mouth open: a sign of stress; check the flow and water parameters.