Torch Coral Not Extending: Reasons Your Euphyllia May Not Be Opening

Is your Torch Coral not extending or opening, and do you want to know why? 

Euphyllia is a group of some of the most beautiful LPS (large stony polyp) corals. These include our favorites – Hammers, Frogspawns, and Torches (Torch Corals). Torch Corals are highly sought after by reef hobbyists because of their mesmerizing large fleshy polyps and tentacles that provide lots of movement. 

When your coral does not extend or open, it is usually a sign that your coral is unhappy, however, monitor this behavior, as it may just be a temporary thing. But, if it continues, there are a few reasons why your Torch Coral may not open.  

Why Do Torch Corals Decide Not To Extend Or Open?

While the sight of seeing your Torch Coral all retracted may seem upsetting and something to make you worried, your coral may be taking some time to rest. Firstly, you could try target feeding, to see if that opens it back up before you start going through possible reasons it is not opening. These reasons include:

  • Poor Water Chemistry 
  • Too Much/Too Little Water Flow
  • Too Much/Too Little Lighting
  • Incorrect Placement
  • Pests Causing Havoc
  • Diseases & Infections

Poor Water Chemistry

The first thing would be to grab your testing kit and check the water parameters, as this is the most common reason corals get “upset”. 

Ideal Water Parameters:

  • Temperature: 75° – 80 °F
  • pH: 8.1 – 8.4
  • Salinity: 1.024 – 1.026
  • Alkalinity: 8 – 11 dKH
  • Nitrates: <10 ppm
  • Phosphates: <0.10 ppm
  • Calcium: 420 – 440 ppm
  • Magnesium: 1260 – 1350 ppm
  • Strontium: 8 – 10 ppm

We must mention magnesium, as it is a really important trace element, especially for your Torch Coral. Many hobbyists recommend running magnesium levels towards the higher range. Keeping your magnesium levels slightly higher will not cause harm to an LPS dominated tank, but low magnesium levels may cause coral bleaching and tissue loss, among other things. We recommend getting yourself a magnesium-specific kit like Aquaforest’s Magnesium Test Kit to keep a close eye on the magnesium concentration. 

Next, how is your salinity looking? You need your salinity to be spot on – 1.025/1.026 is ideal! A salinity refractometer is the best tool to test the salinity of your aquarium water, however, a salinity pen or hydrometer also works wonders. 

Don’t forget to also keep on top of your water changes. Water changes are essential to remove nutrients and replenish vital elements. After each water change, don’t forget to test your water parameters again. 

If you are always struggling with tank stability, we recommend getting yourself a dosing pump. Dosing pumps are great! They deliver precise amounts of fluids automatically into your aquarium, making that next vacation much less stressful!

Too Much/Too Little Water flow

Flow is very important for Torch Corals. So, how do you hit that “sweet spot”? Well, you want your Torch Coral to look like it’s elegantly dancing, not like someone who has been windswept. 

Water flow that is too strong will make your coral retract to prevent them from being pulled a hundred different ways. Water flow that is too strong may also tear their fleshy polyps. But, give them too little water flow, they will be covered in bacteria, uneaten food, you name it. This can lead to their health rapidly declining, and even coral death. 

Their “sweet spot” would be water flow that replicates soft wave actions, enough for their tentacles to gently wave at you, and where the head/base tissue near your Torch’s skeleton is not moving too much.

An interesting discovery from some hobbyists is when Torch Corals suddenly make their tentacles shorter and fatter. If your Torch looks healthy and your water chemistry is on par, then you shouldn’t be too concerned. However, if your Torch Coral is doing this for a long time, you can try increasing the water flow a little and see if that helps make your Torch Coral’s tentacles more “stringy”. 

Too Much/Too Little Lighting

Lighting is important for your Euphyllia’s health and to maintain its vibrant colors. 

Torch corals are photosynthetic and require adequate lighting. This means they rely on photosynthesis for nutrition from the symbiotic algae that live within their tissues, called zooxanthellae.

Providing your Torch with too much light may cause them to shorten their polyps and in severe cases, they may decide to retract and not open. High-intensity lighting can kill your coral in weeks if they start to become white and undergo bleaching. 

In low lighting settings, your Torch Coral cannot provide the Zooxanthellae with enough energy to drive photosynthesis. The Zooxanthellae respond by increasing in numbers to make up for the energy lost from low lighting. This causes the pigments inside your coral to decrease.  If there is not enough light, do not worry, they will soon tell you if by stretching their polyps, not closing them. 

So what is their “happy medium”? As LPS corals require moderate lighting, aim for 150 PAR. Getting a PAR meter is recommended to create a safe-lighting environment for your corals. 

Incorrect Placement 

Is your Torch Coral cramped in a corner or too close to other corals? Poor design and placement may cause your Torch Coral to become stressed, therefore, your coral should be placed in an area that meets all the above needs (light, flow, etc.). 

As Torch Corals have an aggressive temperament, fighting off neighboring corals can be tiring! Your Torch Coral may be stressed from the constant need to attack other corals. You should avoid close contact, so your other corals don’t get a swipe from your Torch’s long sweeper tentacles when they fully extend. It is recommended to give at least 4 inches if Torch Corals are next to each other, and at least 6 inches between different corals. This includes their Euphyllia relatives – Frogspawns and Hammers, as your Torch Coral, are not very welcoming!

You must also be careful not to move your coral around too much, as this can increase stress levels, which may make your coral sick, or in severe cases, your coral may die. Move it once, and then wait a few weeks (or months) to see its reaction. 

Pests Causing Havoc

Critters that hitchhike their way into your aquarium, and naughty, nipping fish, may be to blame for your Euphyllia not opening or extending. 

Dipping corals before adding them to your aquarium is a no-brainer! You should be dipping new corals in a solution like CoralRX or ReVive Coral Cleaner. This way, you reduce the chances of pests hitchhiking their way into your aquarium. 

Fish such as Angelfish are usually not reef-safe. Keep a close eye on any fish and make sure that they are not picking on your Torch Coral. 

Next up, are snails. While some snails are harmless, others will enjoy climbing all over your Torch Coral, taking the occasional bite. Sundial Snails are common Zoanthid pests, but they may also become a nuisance for your Torch Coral. The good news is, snails can easily be manually removed with tweezers. 

Coral-eating flatworms may look harmless, but they negatively affect Torches, Hammers, and Frogspawn Corals. These flatworms are large marine organisms that are hard to miss, however, they are pretty good at a game of “hide-and-seek”. Their favorite spot is between your Torch’s flesh and the bone stalk. As flatworms frequently lay eggs, you may need to regularly dip your corals to completely eradicate them. 

Diseases & Infections

Unfortunately, your Torch Coral is not immune from diseases and infections. 

As a reef hobbyist, you may run into brown jelly disease. Like most coral diseases, the cause of pathogen infections like brown jelly disease is still unknown. The minute you see brown jelly on your coral’s polyps, you must remove it ASAP and start treatment. 


When your Torch Coral doesn’t extend or open, it may be a sign that something is not quite right in your aquarium. This could be anything from too much lighting or water flow, pests, diseases, and everything in between. 

If you feel we have missed anything, and you have any tips on why Torch Corals may not open or extend, drop us a comment below, we won’t bite like those pesky Angelfish!

  • Roy Lee

    I have an unhealthy obsession with reef keeping and maintaining successful tanks. If you haven't noticed from the website, I love everything related to saltwater tanks like coral, fish, and everything else in between. Lee Roy

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