The hammer coral (Euphyllia ancora) features distinctive T-shaped or anchor-shaped tentacle tips that expand during the day, creating a mesmerizing display. Like its Euphyllia relatives (torch and frogspawn), it extends long sweeper tentacles at night that can sting and kill corals within reach. Proper spacing is critical for success.
Quick facts
| Type | LPS (Euphyllia) |
| Difficulty | Moderate |
| PAR range | 100–200 |
| Flow | Medium (indirect) |
| Feeding | Photosynthetic + target fed |
| Growth rate | Moderate |
| Aggression | High (sweeper tentacles) |
| Placement | Mid rock with spacing |
Lighting needs
Provide PAR levels of 100–200 µmol for optimal health and coloration. Moderate accuracy in lighting is sufficient, but consistency matters more than hitting exact numbers. When first placing the coral, start with lower light intensity and gradually increase over 1–2 weeks to prevent light shock.
Spectrum matters as well: a mix of blue (420–480 nm) and white light produces the best fluorescence and growth. Many hobbyists run heavier blue spectrums to enhance coral fluorescence while maintaining enough PAR for photosynthesis.
Flow requirements
Medium, indirect flow works best. The coral should sway gently in the current without being pummeled. Avoid direct powerhead output aimed at the coral. Alternating flow patterns (wave mode) are beneficial for nutrient delivery and waste removal. Adjust flow based on polyp extension—if polyps remain retracted, flow may be too strong.
Placement
Place this coral in the mid rock with spacing area of your aquascape. Warning: This coral has aggressive sweeper tentacles that can extend several inches at night, stinging and killing neighboring corals. Leave at least 4–6 inches of clearance on all sides. Check at night with a flashlight to see the full reach of sweeper tentacles.
Secure the coral to rockwork using reef-safe gel super glue or epoxy. Ensure it is stable and won't topple—falling corals get stressed and damaged. Let the glue cure briefly before returning the frag to the tank.
Feeding
This coral benefits significantly from target feeding. Use a turkey baster or pipette to deliver small meaty foods directly to the polyps: finely chopped Mysis shrimp, Reef-Roids, or Benepets work well. Feed 2–3 times per week after lights dim, when tentacles are most extended. Target-fed specimens grow noticeably faster and display better coloration than those relying solely on photosynthesis.
Fragging
Fragging LPS corals requires more care than soft corals. Use a Dremel rotary tool or bone cutters to separate heads along the skeletal divisions. Avoid cutting through live tissue whenever possible. Dip the fresh cut in iodine solution to prevent infection, then attach to a frag plug with super glue or epoxy. Recovery takes 1–4 weeks. Do not frag stressed or unhealthy colonies.
Common issues
- Tissue recession or bleaching: Usually caused by unstable parameters, excessive light, or chemical aggression from neighboring corals. Investigate recent changes in lighting, dosing, or new coral additions.
- Failure to extend polyps: Check flow strength (too strong?), lighting intensity, and water quality. Recent dipping or transport stress can also cause temporary retraction.
- Pests: Inspect for flatworms, nudibranchs, or other parasites. A prophylactic coral dip (Coral Rx, Bayer) upon introduction prevents most pest issues.
- Slow growth: Ensure adequate feeding, stable alkalinity (8–11 dKH), calcium (400–450 ppm), and magnesium (1300–1400 ppm). SPS corals especially need stable, consistent alkalinity for skeleton building.
Frequently asked questions
Is this coral good for beginners?
This coral is suitable for intermediate reef keepers who have stable water parameters and some experience with coral care. Beginners should start with easier species and work up to this one.
What PAR level does this coral need?
Aim for PAR levels of 100–200 µmol at the coral's position. Use a PAR meter to verify actual light levels in your tank, as fixture specs and manufacturer claims often differ from real-world measurements.
How fast does this coral grow?
Growth rate is moderate. Factors that influence growth include lighting intensity, flow, feeding regimen, and stable water chemistry. Consistent alkalinity and calcium are the primary drivers of calcification rate in stony corals.
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