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Green Star Polyp Coral: Thorough Guide For Beginners

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This article is created to help you know more about green star polyp coral. If you already have a green star or just thinking about buying one, the guide will come in handy.

I talk about every aspect you might be interested in. Such as water parameters, common problem-solving, and more.

Basic Information

Scientific name: Pachyclavularia violaceaCommon name: Green Star Polyp (GSP)Type of Coral: Soft
Average size:up to 1 inch in diameterOptimal Spacing: 3 inchesСomplexity: Easy

Whether you are a beginner who considers a green star polyp coral, or an experienced hobbyist who encountered some problems, you will find all the answers. Just keep scanning the article to find the answer you need. Read subheadings first.

Natural habitat and appearance

Green star polyp corals (GSP) are also known as starburst or daisy polyps. They usually live on the mild slopes of reefs and lagoons. Perfect natural conditions include an environment rich in nutrients and weak water flow. GSP inhabit a wide section in the Indo-Pacific ocean. Covering mainly depths of up to 20 meters. In nature, green star corals can be found both as a single colony and together with other species. Fiji, the Great Barrier Reef, Solomon Islands are the common places to find GSP in nature.

The species have yellowish-green small polyps attached to the purple mat. As pretty much every soft coral, GSP has eight tentacles for each polyp as any other soft coral. (Hint: You can read everything about soft corals here) Tentacles usually form around the “mouth” which is the white center (surrounded by polyps; this formation resembles a star, hence the name). Altogether the appearance is contrast and vivid, which may contribute majorly to the beauty of your reef tank.

Green star polyp coral is also on my list of best beginner friendly soft corals, which is a list you can find right here on my website.

Placement in a Reef Tank

Green star polyp corals live in a wide range of Indo-Pacific. All the way up from Fiji to the Great Barrier Reef. Nature prepared this species to withstand any place in your aquarium. So, there is no principal difference where to put GSP. However, you may want to remember that green star polyp corals grow super fast. They literally can conquer all of the tank in no time compared to other species. GSP can grow over rocks, sand,  and even other corals.

What I suggest is to separate the coral. Create an isolated “island”. That would be a separated average-sized rock where only GSP will grow. I don’t recommend mixing GSP with other corals at the same place. 

I prefer placing GSP, whether at the bottom part or the reef tank’s higher segment. Make sure the water is turbid and the light is not ultra-intense. As for spacing, 2 or 3 inches would be a nice distance to keep. Green star polyp corals are relatively peaceful, so it is not a big problem to drop them upon other species.

Water Quality

I always advise focusing on high-quality water because if you do so, there likely won’t be major problems with corals (as well as with any other marine animal)


Keep calcium about 380 to 420 for green star polyp corals. Measure the value and adjust it slightly if the number varies drastically. I prefer 400ppm as the golden mean rule. You can start from 380, going up step by step. Adding 5 extra ppm every other day should be great for your coral.

Extra tip: You can set a dosing pump to automate the mineral maintenance.


Keep alkalinity in the range of 425 to 450 ppm for green star polyp corals. The same rule as with calcium and any other minerals. If your ppm is out of range, adjust it slightly. Many hobbyists prefer measuring alkalinity in meq\L. Here is a converter for your convenience so that you can set your ppm correctly.

pH (power of hydrogen)

pH level is the absolute champion within problems with corals. Keep your pH in the range of 8 to 8.3 for green star polyp corals. 

If your pH is higher or lower, follow the next quick and easy advice. 

To raise pH — add baking soda. To lower it, consider adding vinegar, lemon juice, or “pH down” products. Don’t rush when adjusting pH. The rule of thumb here is a step-by-step approach.

Additionally, you may want to schedule small (10% to 15%) and big (up to 25%) water changes weekly or any other week. That is done to keep your water clean, balanced, and mineralized.

Temperature and Flow

Green star polyp corals feel great with medium to high water flow and a temperature of about 75 to 80 degrees Fahrenheit. There’s nothing wrong with them if you move a little bit away from those numbers. For example, if the water temperature drops or rises by a couple of degrees, the coral will survive the event with no problem. However, think twice before exposing your tank inhabitants to unnecessary stress. It could have long-term consequences.


For green star polyp corals, stick to the lightning from 100 to 180 PAR. The larger the colony in your aquarium, the more tolerant it will be to aggressive light. For example, younger colonies (hence it’s smaller in size) may be traumatized by 200 PAR, while more massive GSP will have no problems with a little bit of intense light. However, I strongly recommend not to go overboard.

Use metal halides, standard T5, or modern LEDs to provide the light spectrum of 400 to 470nm. That is the standard spectrum for most of the corals. GSP is not an exception. However, they tend to have more bright and vivid polyps if affected by high-quality light. Ideally, you want to keep the 50% blue part of the spectrum for 10 hours and 50% white for 6 more hours, followed by 8 hours of total rest. I switch off the lights for 8 hours daily (fully isolated even from the moon)

Compatibility with Other Species

I advise you to pick 3 to 5 desired fish or other marines first. Once you’ve made that, make sure to read about this fish. Most of the time, peaceful fish are great companions for calm corals.

Here is a short table of some marine animals species compatible with GSP:

EasyMay Cause Problems
Brittle Stars Copper Banded Butterfly 
Ornamental ClamsAnemones 
Yellow WrasseHeliacus Box

As for other corals, GSP fits almost any reef tank. They are peaceful and calm species that deal well with other peaceful or defensive corals. Conventionally, corals can be divided into 3 categories (in terms of compatibility). Those are aggressive, defensive, and passive. Here is a general compatibility chart: 

AggressiveNot compatibleNot compatibleMaybe
DefensiveNot compatibleCompatibleCompatible

As I mentioned, GSP are peaceful corals (Passive). They get along with passive and defensive corals. However, you might have a big problem when poisonous and toxic coral is settled near the GSP. Aggressor corals may extend their poisonous sweeper tentacles to deal damage to the more passive species. If you have aggressive coral in the same tank with a green star coral, make sure to provide 5 to 7 inches of space. If you don’t, the distance doesn’t really matter (not to forget about the fast growth rate)

The Biggest Problem Related to Green Star Polyp Coral

The first time my green star polyp coral retracted, I didn’t know why. I did some research, and guess what… GSP retraction is the most common problem. Why does it happen? There a couple of factors, which are:

  • External stress such as cut, fragging, etc
  • During a nighttime
  • Water quality (minerals, temperature)
  • Lightning 

The simplest thing you can do to treat your green star polyp coral is to check all the above step by step. Start with measuring, adjust to the optimal value and wait a couple of days as corals need time to adapt to new conditions. As the old saying goes: “The quieter you go, the further you’ll get.

Feeding Green Star Polyp Coral

There is no need for targeted feeding. Green star polyp corals contain special algae which live inside the coral’s tissue. Their relationship is described by the scientific word symbiosis, which is a form of mutual interest partnership. 

The algae absorb sunlight during the day and allow the coral to feed on the sun’s transformed energy. In exchange for services rendered, the coral allows microorganisms to reside within its tissues. Through this cooperation, the coral receives up to 80% of all energy. 

Some owners believe that it makes sense to feed the coral additionally. Mostly the same food as for fish is used. In the case of the green star polyp, it is the Phytoplankton. There are some simple truths to keep in mind before you decide to feed the GSP:

  1. You may have little or even no progress at all. Many hobbyists want to speed up the growth rate of corals. That is why extra feeding is so popular. But it would help if you kept in mind that excessive feeding may actually harm your animals. Food wastes remaining in the water promote the spread of microorganisms. If you don’t clean up the debris immediately and there will be favorable conditions for bacteria, algae, etc.
  2. You can overdo your aquarium. Clean water is great but over clean water is not. Some corals like water “a little bit dirty” That is why you may not want to feed the corals as you have to clean the water afterward. Again, the whole procedure may limit your coral’s growth rate. Is that what you want?

Follow these 3 tips if you want to feed no matter what:

  • Mix the food with tank water. Use a separate container to thin the food out
  • Turn off the water circulation in the aquarium
  • Apply the nutrient mixture to the polyps with a turkey baster

Don’t forget to install a protein skimmer and filtration system to eliminate the effects of contamination from feeding the corals with food containing protein and amino acids.

How To Frag Green Star Polyp Coral

Green star polyp corals are super easy to frag. However, it would be best if you didn’t forget about safety. Prepare the next basic equipment to successfully frag GSP:

  • Coral glue and paper towel
  • Frag plugs (or piece of rock from the aquarium)
  • Latex gloves (glue and slime protection)
  • Protective eyewear (Toxin in contact with the eyes can cause partial or complete eyesight loss)
  • Coral dip

To do the procedure, you have to make a cut on the coral to separate a small part of it. 

Use one of the available tools to do this. I like to use a disk. This is because it allows for a quick, clean, and least painful cut on the coral. The less stress you deal — the better.

A quick tip: You can use simpler methods or more complicated ones. For example, tweezers or scalpels are great solutions for beginners. 

After making the cut, dip the coral in disinfectant. Mix the coral dip with tank water in a separate container beforehand. Place the fresh frag in the solution for short-term disinfection. It takes as short as 5 to 10 minutes. I usually stick to 10 minutes, just to be sure.

Once the coral is disinfected, take it out and dry the frag gently with a towel. Dab the coral dip, but do not smear it like you are cleaning the windows. After that, apply regular glue to the frag plugs and connect them to the piece of coral. Allow a few minutes for the glue to set. When the glue is somehow able to hold the frag, you can direct the plug straight into the aquarium. The glue can dry to the end, even in water. The main thing is to place the frag safely underwater so that it doesn’t move.

Useful Tips

  • Always keep your fragging tools clean and neat.
  • Don’t place new frag directly into the tank. Isolate it for 15 minutes first. Then put into the aquarium.
  • Stick to the average lightning, water flow, and temperature, so the coral adapts faster

Green star polyp coral is a no-brainer for reef keepers. Simple enough to keep and propagate yet beautiful and fast-growing. You won’t even notice how it captures the whole tank! Jokes aside… if you are about to start your reef journey, make sure to consider green star polyp coral as a launching platform. It’s one of the ways to have corals without a headache.