Favia Coral

The corals sold in the aquarium trade as "Favia" are closed brain corals that grow in a dome or cushion shape. Each polyp sits in a round corallite with its own wall; it does not share walls with neighboring corallites. This is the easiest way to tell it apart from Favites: in Favites the corallites share common walls like a honeycomb. Fluorescent colonies with neon green centers and brown or cream edges are very popular.

The former Indo-Pacific Favia species were moved to the genus Dipsastraea in a 2012 revision; only Atlantic species now remain in the true genus Favia. Identification to species level is often not possible in the store, so this page covers the genus as a whole. Its trade is subject to CITES Appendix II; choose a maricultured colony or an aquacultured frag.

• Ultra or Rainbow Favia: Collector forms that fluoresce intensely under blue light, with a sharp color contrast between the center and the edge of the corallite.
• Green-brown Favia: The common form with green mouths and brown walls.

It lives in almost every reef environment from the Red Sea to the Central Pacific; some species are the dominant coral in the shallow zones behind the reef crest. In shallow water the corallites are tightly packed, in deep water more widely spaced. Its broad range of habitats explains its adaptability in the aquarium.

• Light: Moderate light, about 100–250 PAR. It also adapts to low light, but fluorescent colors become pronounced under moderate to strong, blue-dominated light.
• Flow: Moderate and variable. There should be enough flow that detritus does not collect between the corallites.
• Placement: The middle zone of the rockwork; leave space beside it because it extends tentacles at night.
• Water parameters: Salinity 1.024–1.026, KH 7–10 dKH, calcium 400–450 mg/L, magnesium 1250–1350 mg/L. It is a tolerant coral; what matters most is that the values stay stable. Nitrate 2–10 mg/L and phosphate 0.03–0.1 mg/L are suitable.

It gets most of its nutrition from light. At night short tentacles emerge from the corallites and catch small organisms in the water. Feeding mysis, brine shrimp or fine-grained coral food once a week after the lights go out improves growth and color. Do not let food rot between the corallites.

Although it looks calm during the day, it extends its tentacles at night, and some colonies develop stinging "sweeper" tentacles several centimeters long. It can also digest a coral it touches with its mesenterial filaments. Leave at least 10 cm of space between it and neighboring corals. Keep it out of reach of more aggressive species such as Euphyllia, Galaxea and Favites.

Dwarf angelfish and some butterflyfish may pick at the tissue. It has no problems with clownfish and most reef fish.

Because of its massive, hard skeleton, it can only be propagated by cutting with a diamond-blade saw. The cut is made between the corallites; each piece should keep several complete corallites. Cut edges heal slowly, so the pieces should be watched for a few weeks under low flow and moderate light. Because growth is slow, large colonies are expensive.

• Bleaching: After a sudden increase in light or a rise in temperature the color turns white. Increase the light gradually and keep the temperature below 27°C.
• Tissue recession: Tissue loss starting at the edges is usually due to contact with a neighboring coral or KH swings.
• Algae between the corallites: If flow is weak and nutrients are high, algae settles between the corallites; increase the flow.