The Euphyllia Trio: Hammer, Octospawn & Frogspawn
If you're building a reef tank with flowing, tentacled LPS corals, three names come up again and again: Hammer Coral (Euphyllia ancora / divisa), Octospawn (Euphyllia paradivisa), and Frogspawn (Euphyllia divisa). These three are closely related members of the Euphyllia family, and the good news for reefers is that they all thrive under virtually identical conditions. Master the care for one, and you've mastered all three.
At Lakeside Reefing, we carry all three — from classic Gold Hammers to rare Octospawn morphs and branching Frogspawn colonies.
What's the Difference Between Them?
- Hammer Coral: Tentacles end in a distinctive hammer or anchor shape. Comes in wall (single large polyp) and branching forms. One of the most recognizable corals in the hobby.
- Octospawn: Tentacles branch and split at the tips, giving a feathery, multi-pronged appearance. Rarer than hammers and highly sought after for their unique look.
- Frogspawn: Tentacles end in rounded, bubble-like tips that resemble a cluster of frog eggs. Branching growth form is most common. Very similar to hammer coral in appearance but with rounder tips.
All three sway beautifully in gentle flow and are stunning under blue LED lighting.
Water Parameters
Stability is the most important factor for all Euphyllia corals:
- Temperature: 76–80°F (24–27°C)
- Salinity: 1.025–1.026
- pH: 8.1–8.3
- Alkalinity (dKH): 8–10 dKH — do not swing more than 0.5 dKH per day
- Calcium: 400–450 ppm
- Magnesium: 1350–1500 ppm
- Nitrate: 5–20 ppm
- Phosphate: 0.05–0.1 ppm
The #1 rule: Alkalinity swings kill Euphyllia. A stable alk of 8 dKH is far better than an alk that bounces between 7 and 10. If you're dosing two-part or running a calcium reactor, dial in your alk first.
Lighting
All three Euphyllia prefer low to moderate light:
- Ideal PAR: 50–150 PAR
- Placement: Lower half of the tank — sandbed to mid-rock
- Spectrum: Blues bring out fluorescent greens, purples, and gold tips; whites show natural coloration
Always acclimate new arrivals to low light first and move them up gradually over 2–3 weeks. Sudden high PAR exposure causes bleaching and tissue recession.
Flow
Gentle, indirect, random flow is ideal for all three:
- Tentacles should sway gently — not whip around or retract
- Avoid direct, high-velocity flow from powerheads pointed straight at the coral
- Wavemakers on random/alternating modes work best
- A consistently retracted coral is almost always a flow problem first
Feeding
All three are active, enthusiastic feeders:
- Target feed 2–3 times per week with mysis shrimp, Reef Roids, LPS pellets, or Coral Frenzy
- Turn off flow for 15–20 minutes after feeding
- Use a pipette or turkey baster to place food directly on the tentacles
- Feed in the evening when tentacles are most extended
Regular feeding accelerates branching, improves coloration, and keeps your Euphyllia looking their best.
Aggression
All Euphyllia have long sweeper tentacles that extend at night to sting neighboring corals:
- Keep at least 6–8 inches of clearance from non-Euphyllia corals
- Euphyllia-to-Euphyllia contact is generally safe — Hammer, Octospawn, and Frogspawn can touch each other without issue and make a stunning mixed display
- Keep away from Mushrooms, Acans, Blastos, Chalice, Favia, and other corals that can't defend themselves
- Clownfish may host in any of the three — generally fine, but watch for excessive activity damaging tissue
Troubleshooting Common Problems
- Brown Jelly Disease (BJD): A fast-moving bacterial infection appearing as brown, slimy spreading tissue. Act immediately — frag below the infection, dip in CoralRx or iodine solution, move to clean water. BJD can destroy a coral in 24–48 hours.
- Coral not opening: Check flow (too high?), lighting (too intense?), alk stability, and look for pests or fish nipping at the tentacles.
- Bleaching: Too much light or a sudden parameter change. Move to a shadier spot and stabilize parameters.
- Tissue recession from the base: Often alk instability, physical damage, or early BJD. Stabilize and watch closely.
- Euphyllia-eating nudibranches: Tiny white slugs that hide at the base of the skeleton and eat tissue at night. Inspect with a flashlight. Treat with a coral dip.
Preparing New Arrivals
We recommend dipping and inspecting all new Euphyllia corals before adding them to your display tank. Get them out of shipping water immediately, into a gentle potassium chloride dip for 10–15 minutes, inspect carefully for pests, rinse, and place in the tank. Read our full guide: How to Prepare New Corals.
Shop Hammer, Octospawn & Frogspawn at Lakeside Reefing
We carry a rotating selection of hand-picked Euphyllia corals — from classic branching Hammers to rare Octospawn morphs and colorful Frogspawn colonies.