Short Answer
- The fastest hammer vs frogspawn check is tentacle tip shape: hammer tips are flattened or anchor-like, while frogspawn tips split into multiple rounded lobes.
- Use a still photo with flow reduced for 30-60 seconds if tentacle movement hides the tips.
- Color names like gold, green, or rainbow do not separate hammer coral from frogspawn.
- If the tips are immature or distorted, label it conservatively as a Euphyllia/Fimbriaphyllia-type LPS until the colony develops.
The main difference is tentacle tip shape
Hammer coral and frogspawn are usually separated by the shape of the tentacle tips, not by color. Hammer coral tips tend to look flattened, curved, or anchor-like. Frogspawn tips usually split into several rounded lobes at the end of each tentacle.
This difference is easiest to see when the coral is expanded but not being pushed hard by flow. Heavy movement can stretch the tentacles and make both corals look more similar than they are.
- Hammer coral: flattened, T-shaped, curved, or anchor-like tentacle ends.
- Frogspawn coral: branched tentacle ends with multiple small rounded tips.
- Both can have green, gold, purple, or multi-color variants, so color should not lead the ID.
Hammer coral vs frogspawn comparison
Use this table as a practical field guide when reviewing a frag photo or checking your own coral in the tank.
| Trait | Hammer coral | Frogspawn coral |
|---|---|---|
| Tentacle tips | Flattened, curved, or anchor-like ends. | Multiple rounded lobes on each tentacle end. |
| Best photo condition | Moderate extension with flow reduced briefly. | Moderate extension with tips visible from the side. |
| Common confusion | Young frags may not show strong hammer shape yet. | Heavy flow can make split tips hard to see. |
| Color usefulness | Useful for describing the specimen, weak for ID. | Useful for describing the specimen, weak for ID. |
How to photograph it for a better ID
A clear side-angle photo usually answers more than a top-down glamour shot.
- Reduce flow briefly for 30-60 seconds if the tentacles are whipping across the frame.
- Take one side angle that shows tentacle tips across several heads, not just one polyp.
- Include the branch base when possible because mature branch spacing can support the ID.
- Avoid relying on vendor color names; record the visible structure instead.
When the ID is still uncertain
Some frags are too young or too stressed to show reliable tip shape. In those cases, a broad label is better than forcing a name from incomplete evidence.
A practical approach is to keep the ID as hammer/frogspawn group, then update it after the coral has expanded consistently for several weeks.
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Sources
References and further reading
FAQ
Frequently asked questions
01What is the easiest way to tell hammer coral from frogspawn?+
Look at the tentacle tips. Hammer coral usually has flattened, curved, or anchor-like tips, while frogspawn has multiple rounded lobes at the end of each tentacle.
02Can hammer and frogspawn be identified by color?+
No. Both corals can appear green, gold, purple, or multi-color under aquarium lighting. Color can describe the specimen, but tentacle shape is a stronger ID clue.
03Why do young frags look hard to identify?+
Young or stressed frags may not show mature tentacle shape consistently. Flow and partial extension can also distort the tips, so repeated observation is useful.
04Should I reduce flow before taking an ID photo?+
Yes, briefly reducing flow for 30-60 seconds can make tentacle tips easier to see. Turn flow back on after the photo so the coral returns to normal tank conditions.