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Euphyllia paraancora is the branching hammer coral. Read how to reliably tell it apart from the wall hammer coral E. ancora and what it needs in the reef tank in terms of light, flow, space and food.
In short: Euphyllia paraancora is the branching hammer coral. Its tentacles with anchor- or hammer-shaped tips resemble those of the wall hammer coral Euphyllia ancora. The reliable difference lies in the skeleton: E. paraancora grows in a branching form with individual, tube-shaped polyp corallites (phaceloid), while E. ancora forms continuous walls and valleys (flabello-meandroid). In the aquarium, the coral needs moderate light, moderate indirect flow, stable water parameters and enough distance from its neighbours.
Profile: Euphyllia paraancora
| Feature | Details |
|---|---|
| Scientific name | Euphyllia paraancora Veron, 1990 – now often listed as Fimbriaphyllia paraancora |
| Common name | Branching hammer coral, anchor coral (branching form) |
| Trade name | Branching Hammer |
| Group | LPS (large polyp stony coral), family Euphylliidae |
| Growth form | branching (phaceloid), polyp corallites approx. 20–40 mm in diameter |
| Distribution | Indo-West Pacific, 0–40 m depth |
| Habitat | Reef areas sheltered from strong wave action |
| Protection status | CITES Appendix II, IUCN Red List: Vulnerable (assessed 2008) |
Taxonomy: Euphyllia or Fimbriaphyllia?
The species was described in 1990 by J. E. N. Veron as Euphyllia paraancora. A molecular genetic study by Luzon and colleagues (2017) split the genus: hammer and frogspawn corals (ancora, paraancora, divisa, paradivisa, yaeyamaensis) have since been placed in the genus Fimbriaphyllia, while torch corals such as Euphyllia glabrescens remain in Euphyllia. A revision of the family by Arrigoni and colleagues (2023) confirms Fimbriaphyllia as a separate genus. In the trade and in many shops, however, the name Euphyllia paraancora is still common. Both names refer to the same species.
Difference from Euphyllia ancora: wall form and branching form
Hammer corals are often confused because the polyps of both species look very similar. The tentacles alone are not enough to reliably distinguish E. ancora from E. paraancora. What matters is the growth form of the skeleton:
- Euphyllia ancora (wall hammer coral, “Wall Hammer”): The skeleton is flabello-meandroid. The polyps sit in elongated, continuous valleys with sharp-edged walls. The colony therefore looks like a wavy, closed band.
- Euphyllia paraancora (branching hammer coral, “Branching Hammer”): The skeleton is phaceloid. Each polyp sits on its own tube-shaped branch. The skeleton resembles that of the torch coral Euphyllia glabrescens.
A practical tip: with very small frags with only one head, the growth form is sometimes not yet clearly recognisable. In this case, look at the skeleton under the tissue. Individual, separate branches indicate paraancora, a continuous wall section with several mouths indicates ancora.
Appearance and colour morphs
The tentacles are tube-shaped and carry the typical anchor-, hammer- or T-shaped tips. In the wild the species is usually light brown to greenish brown. In the aquarium trade you will mainly find green, golden yellow and pink to purple forms as well as specimens with contrasting tips. The colouration can change depending on light and nutrients in the aquarium.
If you want a specific head with exactly this colouration, WYSIWYG corals make sense: you receive the animal shown in the photo.
Care in the reef aquarium
Light
Euphyllia paraancora lives with symbiotic algae (zooxanthellae) and covers a large part of its energy needs through light. Moderate light is sufficient. It usually tolerates higher intensity if you acclimatise it slowly. Place new specimens somewhat lower at first and observe how far the polyps open.
Flow
Flow should be moderate, variable and indirect. The tentacles should move gently but not be pressed flat. Permanently strong, direct flow causes the polyps to retract and can encourage tissue loss.
Placement and spacing
Hammer corals form sweeper tentacles at night and under stress, which can become considerably longer than the normal tentacles. With these they sting neighbouring corals. So plan enough space all round – as a rule of thumb at least 10 to 15 cm, more for large colonies. Many keepers report that hammer and frogspawn corals tend to get along with each other, but this is not guaranteed. Positions on the bottom or in the lower to middle area of the rockwork where the coral can expand are well suited.
Water parameters
Stable parameters are more important than individual target figures. The following values are guidelines for a reef tank with LPS corals:
| Parameter | Guideline |
|---|---|
| Temperature | 24–26 °C |
| Salinity | 34–35 ‰ (specific gravity approx. 1.024–1.026) |
| pH | 8.1–8.4 |
| Carbonate hardness (KH) | 7–9 °dKH |
| Calcium | 400–450 mg/l |
| Magnesium | 1250–1350 mg/l |
| Nitrate | 2–10 mg/l |
| Phosphate | 0.03–0.1 mg/l |
| Light | moderate |
| Flow | moderate, indirect, variable |
| Distance to neighbours | at least approx. 10–15 cm |
We describe the torch coral, a close relative, in detail in our guide Caring for Euphyllia glabrescens.
Feeding
Light is the most important source of energy. Additional feeding with plankton or finely chopped frozen food is accepted by the polyps and can support growth. Feed sparingly and preferably in small portions, for example once or twice a week with reduced flow. Uneaten food pollutes the water.
Propagation
The branching growth form makes propagation comparatively easy. Each polyp sits on its own branch, which you can separate from the colony below the tissue using bone cutters or a fine saw. Cut only through the skeleton if possible, not through living tissue. Then mount the frag on a plug and place it in moderate flow. Over time the heads divide and the colony branches further.
Common problems
- Brown jelly: A brown, gelatinous mass on disintegrating tissue that can quickly spread to other heads. Separate or isolate affected heads as quickly as possible and carefully siphon off affected tissue. Also check water parameters and possible injuries.
- Tissue loss: If the tissue recedes from the skeleton, the cause is often fluctuating water parameters, excessive flow, too much light after placement or stinging contact with neighbours.
- Polyps stay closed: This is normal for the first few days after placement. If the coral stays closed for longer, check flow, light and water parameters.
- Predators and tankmates: Some fish and shrimp pick at the tentacles. Watch the behaviour of your livestock.
CITES and origin
All stony corals (order Scleractinia), including Euphyllia paraancora, are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES). Importing them into the EU requires the appropriate documents. So buy hammer corals from specialist retailers who can prove their origin.
Euphyllia paraancora at Premium Reefing
Currently available from us: Euphyllia Paraancora Lemon Lime (Doublehead) as well as individual WYSIWYG specimens such as Euphyllia Paraancora Holy Grail and Euphyllia Paraancora Orange Stem Tricolor.
You can find more hammer, torch and frogspawn corals in the Euphyllia collection. Newly arrived animals are listed under New arrivals. We ship within Germany and to the EU.
Frequently asked questions about Euphyllia paraancora
What is the difference between Euphyllia ancora and Euphyllia paraancora?
Both have similar tentacles with hammer-shaped tips. E. ancora grows as a continuous wall with valleys (wall hammer coral), while E. paraancora branches with individual branches per polyp (branching hammer coral). They can only be reliably distinguished by the skeleton.
Is the branching hammer coral suitable for beginners?
It is considered an easy-to-keep LPS coral if the tank is established and the water parameters are stable. Moderate flow and enough distance from other corals are important.
How much space does Euphyllia paraancora need?
As a rule of thumb, allow at least 10 to 15 cm distance from other corals. The sweeper tentacles can become considerably longer than the normal tentacles at night.
Do I need to feed the hammer coral?
No, it covers most of its needs through light. However, occasional feeding with plankton or finely chopped frozen food can support growth.
Is the coral now called Fimbriaphyllia?
In current scientific taxonomy, it has mostly been listed as Fimbriaphyllia paraancora since 2017. In the trade, Euphyllia paraancora remains the usual name.
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