Branching Hammer Coral

The branching hammer coral looks just like the hammer coral: its tentacle tips widen like a hammer or an anchor. The difference is in the skeleton; instead of a single-piece wall, each polyp head sits at the end of its own branch (phaceloid structure). Over time the heads split in two and the colony grows like a lush bouquet. Because the skeleton is branching, it is easy to cut; this is why most aquacultured hammer frags are of this species.

With the 2017 molecular revision it was moved from Euphyllia to the genus Fimbriaphyllia; in the hobby it is sold as "Euphyllia paraancora" or simply "branching hammer." Its trade is subject to CITES Appendix II; buying an aquacultured frag is both easy and puts no burden on natural reefs.

It lives in the Western Pacific, especially around Indonesia and the Philippines, on shallow and mid-depth reef slopes sheltered from waves. In the wild it is not as common as its wall-type relative. Its sheltered habitat explains why it wants indirect, gentle movement rather than strong flow in the aquarium.

• Light: Moderate light, about 75–200 PAR. If the light is too strong, the tentacles shorten and the heads stay closed.
• Flow: Moderate, indirect and variable; the tentacles should wave but not be blown about so much that the base of the branches shows.
• Placement: The middle zone of the rockwork. The colony widens as the branches grow; when placing it, plan for 15 cm of space around it.
• Water parameters: Salinity 1.024–1.026, KH 7–10 dKH, calcium 400–450 mg/L, magnesium 1250–1350 mg/L. Keeping KH stable is important. Bringing nitrate and phosphate all the way to zero thins the tissue; a low but measurable level (nitrate 2–10 mg/L) is better.

It is photosynthetic; light is its main source of nutrition. Supplemental feeding speeds up growth and makes new heads form more often: once or twice a week, with the flow turned down, slowly release mysis, chopped seafood or fine-grained coral food over the tentacles. Leftover food pollutes the water, so do not give more than the colony can catch.

Like the hammer coral, it extends stinging "sweeper" tentacles at night and burns the tissue of neighboring corals. Leave at least 15 cm of space in every direction. It is often seen to be kept side by side with the wall-type hammer and frogspawn, but it should stay away from the torch coral. Using activated carbon against the chemicals released by soft corals is helpful.

Clownfish may also host in the branching hammer. Dwarf angelfish, butterflyfish and some hermit crabs may pick at the tentacles; cleaner shrimp, on the other hand, are generally harmless.

It is one of the easiest LPS to propagate in the aquarium. The branch of a healthy head is cut with coral cutters a few centimeters below the head, without touching the tissue. The cut branch is fixed to a frag plug with coral glue and rested for a few days in a low-flow spot. The mother colony heals quickly at the cut. With two-mouthed heads that are about to divide, it is safer to wait until they have split completely before separating them.

• Brown jelly: If slimy brown tissue appears on one of the heads, cut that branch off and remove it immediately; the branching structure makes it easier to stop the disease from spreading.
• Rapid tissue recession: Fast tissue loss of not fully known cause has been reported in Euphyllia and its relatives; watch a newly arrived colony in quarantine.
• Heads not opening: Strong flow, a sudden increase in light, KH swings or contact with a neighboring coral are the most common causes.