Seriatopora caliendrum

Seriatopora caliendrum is a birdsnest coral that grows in a bush shape like its close relative S. hystrix, but its branches are thicker, do not taper toward the tip and end bluntly. The polyps are again arranged in neat rows along the branches. In the wild cream and brown tones are common; in the hobby it is sold mostly in its green form under the name "green birdsnest", and pink forms are also found.

Its care is almost the same as S. hystrix: once acclimated to the aquarium it grows fast and is easy to propagate, but in the first weeks it is sensitive to shipping and sudden changes. Thanks to its thick branches, it breaks less often in the flow and during maintenance.

The IUCN assesses this species as "vulnerable" in the wild. Trade in stony corals is already subject to CITES Appendix II; always choose an aquacultured frag instead of a wild-collected colony.

It lives from East Africa and the Red Sea to the Western Pacific on shallow reef slopes, especially on back-reef slopes sheltered from waves, down to a depth of about 25 m. It is less common than S. hystrix. Because the tops of its corallites project like hoods, large colonies can resemble a thin-branched Stylophora.

• Light: Moderate light; roughly 150–250 PAR. The green color stays bright in this range. A new frag should be kept under lower light for about a week.
• Flow: Moderate, random and indirect flow; enough that detritus does not build up between the branches, but not so much that it strips the tissue.
• Placement: The middle or upper part of the rockwork, with 10 cm of space around it.
• Water parameters: Salinity 1.025–1.026, temperature 25–26.5°C and should not exceed 28°C. KH 7–9 dKH, calcium 400–450 mg/L, magnesium 1250–1400 mg/L, nitrate 2–10 mg/L, phosphate 0.02–0.08 mg/L. Sudden swings in KH trigger tissue loss from the bases of the branches.

It is photosynthetic; most of its energy comes from the zooxanthellae algae in its tissue. Extra feeding is not needed, but fine powdered food or rotifers given once or twice a week can speed up growth. Monitor nitrate and phosphate after feeding.

It is a peaceful coral. Over time its dense branches shade neighboring corals and grow toward them. Long-tentacled LPS, Galaxea and fast-spreading soft corals harm it; leave at least 10 cm of space.

Dwarf angelfish may pick at the polyps. Wild colonies may carry small guard crabs (Trapezia), which do not harm the coral. Large hermit crabs and sea urchins can break the branches.

Branch tips 3–4 cm long are snapped or cut off and attached to a frag plug with gel glue. Because the branches are thick, the cut is clean and the pieces attach to the plug quickly. This species can also release larvae (planulae); small colonies may appear on their own in the aquarium.

• Tissue loss from the base (STN): Whitening that starts at the base of the branches; KH swings, depleted nutrients and shaded inner branches are the main causes.
• Rapid bleaching: A rise in temperature and sudden changes in light can bleach the colony within a few days. Keep the temperature stable and make lighting changes slowly.
• Browning: Light is too low or nutrients are high.
• Broken branches: Do not throw broken pieces away; you can get a new colony by gluing them to a frag plug.