Frogspawn Coral

About Frogspawn Coral

Hammer Coral (Euphyllia ancora) is a large polyp stony (LPS) coral found across the warm reefs of the Indo-Pacific. Its defining feature is a set of long, flowing tentacles that move hypnotically in the current, each tipped with a distinctive T- or anchor-shaped end. Color morphs range from neon green and gold to blue and purple, with fluorescent green variants being particularly sought after by hobbyists. While generally calm in appearance, it does extend sweeper tentacles that can sting neighboring corals, so thoughtful placement is essential in a reef layout. Its greatest appeal is the living, dynamic quality it brings to a tank—swaying gently with the flow and filling the aquascape with both movement and vibrant color. With attention to stable alkalinity, gentle indirect flow, and early intervention if disease appears, Hammer Coral is a rewarding and approachable species for those venturing into LPS reef-keeping.

7 things to know before welcoming a Frogspawn Coral

1. 1Water Stability Comes First

   Hammer Coral is sensitive to sudden swings in alkalinity (dKH), calcium, and magnesium. Aim for 8–9 dKH and 400–450 mg/L calcium, and test at least once a week. Avoid rapid corrections, as abrupt changes can cause tissue recession.

2. 2Moderate Flow Is Ideal

   A gentle, indirect flow that causes the tentacles to sway naturally is ideal. Direct, high-velocity flow can damage the tentacles and cause polyps to remain retracted. Position powerheads to create turbulent, indirect circulation rather than a direct blast.

3. 3Medium to Low Light

   Hammer Coral prefers medium to low light rather than intense illumination. Placing it in the middle or lower section of the tank works well, and acclimating it to lower light first reduces stress. While it relies on zooxanthellae for nutrition, excessive light can trigger bleaching.

4. 4Aggression Toward Neighbors

   Hammer Coral extends sweeper tentacles that can sting and damage neighboring corals. Keep at least 15–20 cm of space between it and other corals. Even other Euphyllia species should not be allowed to make contact, as stinging can cause tissue damage.

5. 5Target Feeding Boosts Growth

   While it can survive on photosynthesis alone, target feeding with mysis shrimp, copepods, or coral-specific foods once or twice a week noticeably accelerates growth. Turn off flow briefly during feeding and deliver food directly to open polyps for best results.

6. 6Watch for Brown Jelly Disease

   Hammer Coral is notably prone to brown jelly disease, a rapid tissue necrosis caused by bacterial infection. If you notice brown, mucus-like material on the coral, remove it with a syringe and isolate the colony immediately. Poor water quality and physical damage are common triggers.

7. 7Setup and Running Costs

   Due to its popularity, a single frag can range from roughly ¥3,000 to ¥30,000 or more depending on size and coloration. Ongoing costs include electricity for lighting and pumps, salt mix, and dosing additives. Investing in a well-cycled, stable tank from the start reduces long-term maintenance expenses significantly.

Frequently asked questions about Frogspawn Coral

Q.What tank size is needed for Hammer Coral?

A.A tank of at least 60 cm (approximately 57 liters) is recommended. Larger water volume helps maintain stable parameters, which directly benefits coral health. Nano reef setups are possible but require more diligent monitoring.

Q.Why do the polyps stay retracted all the time?

A.Common causes include poor water quality, excessive direct flow, overly intense lighting, and physical stress. Start by checking alkalinity, ammonia, and nitrite levels, and verify that flow is not hitting the coral directly. Acclimation to a new environment can also take several days to a week.

Q.Can Hammer Coral be kept with other corals?

A.Yes, but adequate spacing is essential to prevent sweeper tentacle contact. It can sting both hard and soft corals placed too close. Even other Euphyllia species such as Torch or Frogspawn should not be allowed to touch, as chemical and physical contact causes tissue damage.

Q.Does Hammer Coral propagate or split?

A.Healthy colonies gradually branch out and grow over time, allowing for natural propagation. Manual fragging by cutting is also possible, but cut surfaces are susceptible to brown jelly disease, so use clean tools and allow frags to recover in a separate, stable environment.

Q.My Hammer Coral is turning brown—is that normal?

A.Browning is often caused by an increase in zooxanthellae density, commonly linked to excessive nutrients or overly intense light. While not immediately harmful, adjusting lighting intensity and nutrient levels can help restore vibrant coloration. Note that this differs from brown jelly disease, which involves visible mucus and rapid tissue loss.

Useful tools for Frogspawn Coral care

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