Top 10 Most Difficult Corals To Keep in a Reef Tank
Some corals are hard to keep for obvious reasons. They might need constant feeding, extremely stable water chemistry, or very specific lighting and flow. Others are a little more surprising. Sometimes the coral itself is not impossible, but various smaller factors like shipping stress, poor placement, pests, aggressive neighbors, or questionable sourcing add up to turn your beautiful new addition into a frustrating loss.
Plenty of hobbyists keep the corals on this list successfully, and if you have your eye on one of them for your reef tank, knowing why they're challenging and what usually goes wrong can give you a better chance of long-term success.
Quick Answer: The 10 Hardest Corals To Keep
Jump to any coral below to learn why it can be challenging and what gives you the best chance of success.
Why Are Some Corals Hard To Keep?
Corals can be difficult for a bunch of different reasons. Some have delicate tissue that is easily damaged. Some ship poorly. Some are collected from the wild, cut into small frags, moved through several systems, and then sold before they have really had time to settle into aquarium life.
Placement can also make a huge difference. A coral that looks like it belongs on the sandbed might actually come from rock walls in the wild. A coral that looks peaceful might still sting a neighbor. A coral that looks amazing under store lighting might shift color once it has been in your tank for a few weeks.
When possible, aquacultured corals are usually the safest bet. They are already adapted to aquarium conditions, often handle shipping better, are usually more predictable in coloration, and may come with a lower risk of hidden pests when purchased from a reputable source.
10 Difficult Corals To Keep in a Reef Tank
1. Plate Corals
Why They’re Difficult
Plate corals can be surprisingly picky. They have delicate flesh, long flowing tentacles, and they can be easily irritated by sand, cleanup crew, or too much contact with nearby corals. They also tend to get lumped together as one group, even though different plate-like corals can have very different placement needs.
What Usually Goes Wrong
One of the biggest mistakes is assuming every plate coral belongs on the sandbed. Some do, but many plate-like corals naturally live on rockwork or rock walls. When the wrong coral is placed on the sand, it can get buried and slowly start receding around the edges.
Best Chance Of Success
Proper identification is key. Before placing a plate coral, figure out exactly what type you have and research where that specific coral is usually found. If its natural habitat isn't on the sandbed, give it a secure spot on the rockwork where sand and cleanup crew are less likely to bother it.
2. Deep Water / Smooth Skin Acropora
Why They’re Difficult
Deep water and smooth skin Acropora can be especially tough during the first few weeks in a new tank. Once established, some can do well, but getting them through the initial acclimation period is often the hard part.
What Usually Goes Wrong
These Acropora can look fine for a day or two and then suddenly start losing tissue. This is often called Rapid Tissue Necrosis, or RTN for short. Smaller frags can be especially fragile, and freshly shipped pieces may not handle the transition well. Even when other Acropora in the tank are doing fine, smooth skin varieties can still struggle.
Best Chance Of Success
Start with a larger, healthy, well-established piece when possible. Buying locally can help because the coral avoids another round of shipping stress. Start it in lower light than more light-hungry Acropora, then carefully move it into stronger light as it settles in and shows signs of stability.
3. Fancy Torch Corals
Why They’re Difficult
High-end torch corals can be much harder to keep than more common, well-established varieties. The issue is not always the coral type itself. A big part of the challenge can come from sourcing, shipping, recent fragging, and how long that strain has actually been adapted to aquarium life.
What Usually Goes Wrong
Some torches can be prone to poor extension, tissue recession, and brown jelly disease. When one head starts to go, the problem can spread quickly, especially in a crowded torch garden. Newer named varieties with big price tags may also be freshly imported or recently chopped from a wild colony.
Best Chance Of Success
Look for aquacultured or well-established torch corals that have already proven they can thrive in captivity. Give each piece room, avoid packing too many new torches together at once, and be cautious with the latest and greatest named corals if they have not been in the hobby very long.
4. Collector Hammer Corals
Why They’re Difficult
Collector hammer corals can fall into the same general problem area as "fancy" torch corals. Common aquacultured hammers and frogspawn are rather easy to keep, but some high-end collector varieties are more finicky, slower growing, and less forgiving.
What Usually Goes Wrong
Brown jelly disease, tissue recession, poor adaptation to captivity, and stress from recent cutting can all be problems. Some collector Euphyllia may be wild collected, quickly named, cut into small pieces, and sold before they have had enough time to settle.
Best Chance Of Success
Choose aquacultured pieces whenever possible. Locally grown hammers, frogspawn, and octospawn from another hobbyist or trusted store are usually a better choice than a freshly imported high-dollar frag. Stable parameters, moderate flow, and enough space between corals will also help.
5. Non-Photosynthetic Corals
Why They’re Difficult
Non-photosynthetic corals are difficult because they do not rely on light the same way many common reef corals do. Instead, they need regular feeding to survive. That sounds simple until you realize just how much food some of them need and how quickly that food can affect water quality.
What Usually Goes Wrong
The challenge is balancing food and filtration. If there is not enough food suspended in the water, the coral slowly starves. If you feed heavily enough to keep the coral happy, excess food can break down into ammonia, nitrate, and phosphate. Filtration can remove the food the coral needs, but leaving too much food in the tank can create nutrient problems.
Best Chance Of Success
Start with the more manageable options, like sun corals or Dendrophyllia, before jumping into difficult non-photosynthetic gorgonians or sea fans. A dedicated NPS system is usually the best approach. Automated feeding, strong filtration, and frequent maintenance can all help, but these corals are best for hobbyists with the time and commitment to feed consistently.
6. Xenia / Green Star Polyps
Why They’re Difficult
Xenia and green star polyps are usually considered beginner corals, which is exactly what makes them such a funny addition to this list. In some tanks, they grow like weeds. In others, they melt away for no obvious reason.
What Usually Goes Wrong
The challenge can go in either direction. If they love your tank, they'll spread across rockwork and become difficult to control. If they don't like your tank, they might shrink, melt, or refuse to grow even when other supposedly more difficult corals are doing great.
Best Chance Of Success
Treat them like corals that need a plan. If you want to keep Xenia or GSP, isolate them on their own rock or place them somewhere you can control their spread. If they struggle, don't assume your whole tank is failing. These corals can behave very differently from one aquarium to the next.
7. Large Meaty Corals
Why They’re Difficult
Large meaty corals like Cynarina, Acanthophyllia, Scolymia, and some Micromussa can be beautiful, but they are not always easy. Their soft, fleshy tissue can be damaged during shipping, handling, or placement, and that damage can quickly become a bigger problem.
What Usually Goes Wrong
The visible flesh is delicate, but the skeleton underneath can also hide pests. Worms and other boring organisms can live deep inside the skeleton where they are hard to see and difficult to remove with a normal dip. A coral may look fine for weeks or months before slowly withering away because something is irritating it from inside the skeleton.
Best Chance Of Success
Inspect these corals carefully before buying. Look for healthy tissue, avoid pieces with obvious skeleton damage, and be gentle during placement. Keep the fleshy tissue away from sharp rock edges, aggressive neighbors, and fish or inverts that may pick at it. When aquacultured options are available, they are usually worth considering.
8. Yellow Corals
Why They’re Difficult
This is a bit of a broad category, but in modern reef tanks with heavy blue lighting, yellow corals can look dull, green, brown, or washed out instead of bright yellow.
What Usually Goes Wrong
Yellow pigmentation doesn't always show well under blue lighting. Blue-heavy reef lights can make yellow corals look less impressive and may bring out green fluorescent tones instead. A Yellow Fiji Leather, for example, can look amazing under a fuller daylight spectrum but much less yellow under deep blue lighting.
Best Chance Of Success
If you want yellow corals to look their best, run a fuller spectrum lighting schedule for at least part of the day. Yellow corals can be a great choice for hobbyists who like a more natural daylight look, T5 lighting, metal halide lighting, or a balanced LED spectrum.
9. Elegance Corals
Why They’re Difficult
Elegance corals are one of those corals that can look incredible in the store and then become a serious challenge at home. Wild collected elegance corals, especially pieces that have been cut from larger colonies, can be especially difficult.
What Usually Goes Wrong
Placement is tricky. Put them on the sand and they may not be happy. Put them on the rock and their inflated tissue can rub against sharp edges, get cut, and become infected. Long wall-shaped pieces that were chopped from a larger colony can have a hard time recovering from that initial cut.
Best Chance Of Success
Look for aquacultured elegance corals or long-established pieces from another hobbyist when possible. If choosing a wild collected specimen, rounded pieces with a natural attachment point tend to be more promising than freshly cut wall-shaped sections. Give the coral a stable place where the tissue can expand without rubbing against rock.
10. Goniopora
Why They’re Difficult
Goniopora are incredibly popular, and for good reason. A healthy Goniopora with long flowing polyps can be one of the most eye-catching corals in a reef tank. The challenge is that they can be hit or miss, especially with newer high-end varieties or pieces that are not fully aquacultured.
What Usually Goes Wrong
Some Goniopora don't tolerate fragging well. Others may recede after shipping or slowly decline if they aren't adapted to aquarium life. They also don't always play nicely with each other. Even two true Goniopora can sometimes sting or irritate each other when their polyps touch.
Best Chance Of Success
Choose aquacultured Goniopora whenever possible. Give each coral plenty of room, especially if you are mixing different colors or varieties. Don't assume every Goniopora can touch just because you have seen tightly packed Goniopora in frag systems online. Some can, but others need a surprising amount of space.
Explore Top Aquacultured Picks from ORA
Adam has been reef keeping since 2010 and got his start on the Bulk Reef Supply Customer Service team. He believes the best tanks are built around what you enjoy, not what’s trending. Adam is especially interested in simplifying the hobby, exploring the latest gear, and helping others focus on long-term success over chasing perfection.
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