Reef Tank Coral Identification – The Ultimate Guide To Naming
Walking into a local fish store can feel like stepping onto another planet. The glowing blues, vibrant greens, and pulsating shapes are mesmerizing, but for many hobbyists, it is also incredibly overwhelming.
You might see a beautiful specimen and wonder, “Is that a hammer coral or a frogspawn?” or “Will this coral sting its neighbors?” Understanding reef tank coral identification is the first step toward becoming a successful reef keeper.
In this guide, I am going to help you demystify the world of corals. We will break down the major categories, look at specific growth patterns, and give you the confidence to know exactly what you are putting into your glass box.
Why reef tank coral identification Matters for Your Tank’s Health
Identifying your corals isn’t just about showing off your knowledge to friends. It is a fundamental part of animal husbandry. Every coral has specific needs regarding light, flow, and placement.
If you misidentify a high-light Acropora as a low-light Leptoseris, you might accidentally bleach your new investment. Knowing the species helps you anticipate how large it will grow and how aggressive it might be.
Furthermore, some corals, like certain Palythoa species, can be toxic. Proper identification ensures you handle your reef inhabitants safely, protecting both your health and your aquarium’s ecosystem.
Understanding the Three Main Categories
Before we dive into specific species, we need to look at the three “buckets” most hobbyists use to categorize corals. While these aren’t strictly scientific taxonomic ranks, they are the gold standard in the hobby.
The three categories are Soft Corals (Softies), Large Polyp Stony (LPS) corals, and Small Polyp Stony (SPS) corals. Identifying which bucket a coral falls into is 50% of the battle won.
Generally, if it sways in the current and has no hard skeleton, it is a softie. If it has a hard skeleton and big, fleshy polyps, it is LPS. If it looks like a hard, colorful stick with tiny dots, it is likely SPS.
The Beginner’s Favorites: Identifying Soft Corals
Soft corals are often the entry point for new reefers. They are generally hardier, more forgiving of water chemistry swings, and provide a lot of movement in the tank.
When you are looking at soft corals, you won’t see a calcium carbonate skeleton. Instead, they use sclerites—tiny, needle-like structures—to maintain their shape. They feel squishy or leathery to the touch.
Zoanthids and Palythoas
These are perhaps the most popular corals in the world. They look like small, colorful mats of “flowers” or “buttons.” Each individual “flower” is a polyp connected by a common tissue called a coenenchyme.
Zoanthids (Zoos) are usually smaller and more brightly colored. Palythoas (Palys) tend to be larger, often incorporating sand into their tissue, and can be more aggressive growers.
Keep an eye on the “fringes” (tentacles) around the edge of the disk. If they are long and thin, you are likely looking at a Zoanthid. If the disk is wide and the tentacles are short, it might be a Paly.
Leather Corals (Sarcophyton and Sinularia)
Leather corals are the giants of the soft coral world. The Sarcophyton, or Toadstool Leather, is easy to spot because it looks exactly like an underwater mushroom with a thick stalk and a flat cap.
The Sinularia (Finger Leather) has a more tree-like appearance with long, finger-like projections. These corals often “shed” a waxy layer of skin to clean themselves, which is a key identification behavior.
If your coral looks like a piece of tan or green leather and occasionally retracts its polyps for a few days to look shiny, you’ve definitely got a Leather coral on your hands.
Xenia and Star Polyps
Pulsing Xenia is famous for its “clapping” motion. If you see a soft, fleshy coral where the polyps are constantly opening and closing rhythmically, that is Xenia. No other coral moves quite like it.
Green Star Polyps (GSP) are often mistaken for grass. They have a bright purple base (mat) and neon green tentacles. When they retract, they leave behind a smooth, purple surface that can cover rocks or even the back glass.
The Showstoppers: Identifying LPS (Large Polyp Stony) Corals
LPS corals are the bridge between beginners and experts. They have a hard, stony base but are covered in large, fleshy tissue that inflates with water. This makes reef tank coral identification for this group particularly fun.
These corals are known for their “sweeper tentacles”—long, stinging hairs they send out at night to clear space. If you see a coral with a hard skeleton but very puffy “meat,” it is LPS.
The Euphyllia Family (Hammers, Torches, and Frogspawns)
This is the “holy trinity” of the LPS world. They all share a similar skeletal structure but have very different tentacle tips. Learning to tell them apart is a rite of passage for reefers.
Hammer Corals: Look at the tips of the tentacles. If they are shaped like a “T,” a crescent moon, or a literal hammer, you have a Hammer coral (Euphyllia ancora or paraancora).
Frogspawn Corals: These have tentacles with multiple little “balls” or nodules on each strand, resembling a cluster of frog eggs. It looks much busier and more branched than a hammer.
Torch Corals: These have long, single tentacles with a single round ball at the very tip. They look like a head of hair swaying in the wind and are generally the most aggressive of the three.
Acanthastrea and Micromussa
Often just called “Acans,” these corals look like colorful, fleshy donuts. They grow in colonies where each polyp has its own distinct circular shape and a “mouth” in the center.
They are known for their incredible “warpaint” colors—stripes of red, orange, purple, and green. If you see a low-growing, fleshy colony that looks like a tray of colorful cinnamon rolls, it’s likely a Micromussa lordhowensis.
Brain Corals (Favia, Platygyra, and Trachyphyllia)
Brain corals are easy to identify because they look… well, like brains. They have winding ridges and valleys. Platygyra is often called the “Maze Brain” because its ridges are continuous.
Trachyphyllia (Open Brain Corals) are usually found on the sand bed. They have a very large, fleshy mantle that can expand to three or four times the size of their skeleton, often appearing in neon reds and greens.
The “Sticks”: Identifying SPS (Small Polyp Stony) Corals
SPS corals are often considered the “endgame” for reef keepers. They require pristine water, high light, and high flow. Identifying them involves looking at growth patterns and the tiny polyps that dot their surface.
Unlike LPS, the tissue on SPS is very thin. You are mostly seeing the colorful skeleton covered in a thin layer of living skin. These corals are often rigid and can be quite sharp.
Acropora: The King of the Reef
Acropora is the most diverse genus of coral. They are usually identified by their branching structure and the presence of a “terminal polyp” or “axial corallite” at the very tip of each branch.
If you see a coral that looks like a complex bush or a stag’s horn with a distinct “hole” or “point” at the end of every branch, it’s an Acropora. They come in every color of the rainbow, from “Oregon Tort” blue to “strawberry shortcake” pink.
Montipora: The Versatile Grower
Montipora corals are a bit easier than Acropora. They don’t have that prominent tip at the end of the branches. Instead, they grow in three main ways: plating, encrusting, or branching.
The “Montipora Cap” (Montipora capricornis) is a classic. It grows in swirling, thin plates that look like flower petals. If you see a coral that looks like a thin, colorful potato chip growing out of a rock, it’s a plating Montipora.
Pocillopora and Seriatopora
Pocillopora (Cauliflower Coral) has a very fuzzy appearance because its tiny polyps are almost always extended. It grows in tight, bushy clumps and is very hardy for an SPS coral.
Seriatopora (Birdsnest Coral) is identified by its very thin, sharp branches. The branches often come to a needle-like point. If the branches are thin and the coral looks like a tangled mess of colorful sticks, you’ve found a Birdsnest.
Advanced Tools for reef tank coral identification
Sometimes, looking with the naked eye isn’t enough. As you get deeper into the hobby, you might need a few “expert” tricks to tell similar species apart, especially when corals are stressed and lose their color.
One of the best tools for reef tank coral identification is a macro lens for your smartphone. By taking a high-detail photo, you can zoom in to see the shape of the corallites (the stony cups the polyps sit in).
For example, the difference between a Favia and a Favites is that Favites share walls between polyps, while Favia have their own separate walls. You often need a close-up photo to see this clearly!
The Role of Lighting in ID
Be careful: lighting can lie to you! A coral under heavy actinic (blue) light will look completely different than it does under white light. Many corals also fluoresce, changing their appearance.
When trying to identify a coral online or in a forum, always try to provide a photo under “daylight” settings (roughly 10,000K to 12,000K). This shows the true pigmentation of the tissue rather than just the fluorescent proteins.
Also, remember that “browning out” is common. If a coral isn’t getting the right light, it may turn brown as it produces more zooxanthellae. Don’t let the brown color fool you; look at the skeletal structure instead.
Common Identification Mistakes and Lookalikes
Even experts get stumped sometimes. There are several “lookalike” pairs in the reefing world that cause constant confusion for beginners and intermediate keepers alike.
One common mix-up is the Cabbage Leather vs. Plating Montipora. At a distance, they both look like leafy plates. However, the Cabbage Leather is soft and floppy, while the Montipora is rock-hard and brittle.
Another is the Goniopora (Flowerpot Coral) vs. Alveopora. They both look like a bouquet of long-stemmed flowers. To tell them apart, count the petals (tentacles) on a single polyp. Goniopora has 24, while Alveopora has 12.
Safety First: The Palytoxin Warning
I cannot stress this enough: identification is a safety issue. Some Palythoa and Zoanthid species contain palytoxin, one of the most potent non-protein toxins known to man.
If you identify a coral as a “Paly,” never boil the rock it is on, and never scrub it under hot water. Always wear gloves and eye protection when fragging or moving these corals. Being a smart aquarist means being a safe one.
Frequently Asked Questions (FAQ)
How can I improve my reef tank coral identification skills?
The best way is to look at “What is this?” threads on forums like Reef2Reef or participate in local reef club meetups. Seeing corals in person and asking experienced reefers is invaluable.
Can corals change their shape as they grow?
Yes! This is called phenotypic plasticity. A coral in high flow might grow thick, short branches, while the same species in low flow might grow long, thin branches. Always look at the polyps for a more reliable ID.
Is there an app for identifying corals?
There are several apps like “Build Your Aquarium” or “Reef Scan” that attempt to use AI for ID. However, they aren’t 100% accurate yet. Use them as a starting point, but verify with a guide or an expert.
Does the color of the coral tell me the species?
Rarely. Most corals come in a vast array of “color morphs.” For example, a “Dragon Soul” Torch and a “Gold” Torch are the same species (Euphyllia glabrescens), just with different pigments.
What should I do if I can’t identify a coral?
If you are unsure, place it in a “neutral” spot—middle of the tank, moderate light, and moderate flow. Watch its reaction over 48 hours. If it reaches for light or retracts from flow, adjust accordingly.
Conclusion
Mastering the art of reef tank coral identification is a journey, not a destination. Even after years in the hobby, I still find specimens that make me scratch my head and reach for my reference books.
Remember to start with the big categories: Is it soft, LPS, or SPS? From there, look at the growth pattern, the polyp shape, and the tentacle count. Don’t be afraid to ask for help from the community—we were all beginners once!
By taking the time to identify your corals properly, you are providing them with the best possible chance to thrive. You’ll be able to create a stunning, harmonious underwater garden that will be the envy of every guest who sees it. Happy reefing!
