Green Star Polyps Care (GSP Coral Guide)

Updated: Jan 2023

Green Star Polyps (GSP) are one of my favorite corals and are perfect for beginners.

The scientific name for Green Star Polyps is Pachyclavularia Violacea.  They are also known as Daisy Polyps or Star Polyps.

GSP corals are very durable and easy to keep in reef tanks. They don’t require pristine water quality or need a specific water flow or lighting.

They can handle a range of tank conditions and grow fairly quickly.

Green Star Polyps care is easy providing you follow a few simple rules.

Green Star Polyps facts and care requirements

  • Origin: Islands of the Indo-Pacific (Fiji, Tonga, Great Barrier reef)
  • Coral type: Soft
  • Lighting: Low to medium
  • Water flow: Medium to high
  • Care level: Easy
  • Aggression: Can grow over other corals but does not sting
  • Feeding: Relies on zooxanthellae and can be fed phytoplankton

Did you know?

Green Star Polyps are Octocorallians. They belong to a class of corals that have 8 tentacles per polyp. 

GSP Appearance

Green Star Polyps are in mat form which is bright purple and sometimes reddish in color. GSP tentacles are usually bright green, yellow, or pale green. It is easy to see the purple mat at night when the lights are off. The GSP coral tentacles look stunning under actinic lighting as the green color really pops.

Their tentacles are thin and smooth and love to sway in the water flow. They surround a center opening, or mouth, that is often a different color like white, adding more attractiveness to these amazing mat polyps.

green encrusting star polyps

How To Feed Green Star Polyps

GSP corals will grow and do well under normal conditions. They don’t need to be spot fed on a regular basis but they will appreciate it so feel free to feed them periodically. They are photosynthetic and get their food from zooxanthellae.

They will absorb dissolved organic matter from the water column and will pull in particles to feed on. It’s true that target feeding will help their growth rate, but they tend to do just fine under normal reef tank conditions.

It is good to feed your tank phytoplankton which GSP will absorb and feed off of.

How Much Water Flow Is Required For GSP?

Green Star Polyps should be placed in a moderate flow area of your tank.

As the tentacles grow and extend, they love to wave with the water flow. If the water movement is pulsing or on a variable flow, the GSP will do quite well. If you are using constant flow powerheads or wavemakers, they will do fine unless the water flow is too strong. In that case, the GSP will tend to stay closed up and not open very well.

Lighting Requirements For GSP

As mentioned earlier, GSP doesn’t require high end or powerful lighting.

They will do just fine under a low to moderate light source.

I prefer to use LED’s as the polyps look amazing under the actinics of the LED light. You can also use T5 lighting as well.

The Kessil Tuna Blue A80 is a great light for small nano tanks perfect for GSP corals.

How Long Does GSP Take To Spread? What Is Their Growth Rate?

Green Star Polyps are considered to be a fast-growing coral. It doesn’t take long for them to spread quickly under normal reef tank conditions.

Expect GSP coral to grow at a rate of 1-2″ each month. 

They can be placed anywhere in your tank and will grow onto adjacent pieces of rock and even your aquarium equipment and glass.

If that is a concern, you will need to be careful about their placement. It is common for them to attach to glass and start growing up the back wall of your tank. Which I personally like but not everyone is a fan of that.

Growing Green Star Polyps on your glass is actually something that many hobbyists try to do as they look great flowing on the glass wall. It won’t take long for a small frag of GSP to become a huge colony growing on your aquarium glass or equipment.

It will easily grow on rocks and substrate. I am a fan of bare bottom tanks, and love to see GSP growing on the bottom glass.

Check out this awesome reef tank with an amazing back wall covered in GSP:

Ideal Water Parameters For Green Star Polyps

Normal tank conditions for keeping GSP healthy should be the same as many other soft corals. You don’t need to be overly picky about perfect water quality with these.

  • Salinity: 1.025
  • Temperature: 78-79F
  • Calcium: 400-450ppm
  • Alkalinity: 8-11 dkh
  • Magnesium: 1200-1350ppm
  • Phosphates: 0

Why Are Green Star Polyps Closed And Not Opening-Up?

It is very common for GSP to be closed up under a few conditions. When they are not opening, you will see their purple mat without any green tentacles showing.

There are many reasons conditions why GSP won’t open. Here are a few:

  • If the coral is under stress (poor water quality, high flow, stress form fish or other corals)
  • Being fragged or picked up and touched
  • At night if lights are off

You might notice that only part of the coral or just a few polyps will retract while the rest stays open, for example, if you are just moving it to another position. Under high stress, the whole colony will close up.

green star polyps not opening

Read more: 11 reasons why Green Star polyps will not open up

My GSP coral showing the purple mat when polyps not open

How To Frag Green Star Polyps

Fragging GSP is very easy. Probably one of the easiest corals to frag and not harm. You can take the purple mat and use a razor blade, knife, or scissors to cut the shape and size you like. The new frag can be glued to a frag plug or rock rubble and will grow quickly. I normally frag my larger colonies into smaller frags and within no time I will have many colonies forming.

Where To Buy Green Star Polyps And Cost

Another great thing about GSP is the fact they are easy to find and cheap to buy. As mentioned, these corals are very common to see in home aquariums. Most local saltwater fish stores will carry frags or small colonies of GSP. If not, they can be ordered in easily. Expect to pay around $10 for small frags and $25-$50 for small to medium-sized colonies.

You can also look online to buy them. Check out and

How long does it take for Green Star Polyps to open?

There are a few different factors that determine the length of time it takes GSP corals to open. Water parameters, lighting, water movement to name a few.

Expect them to take anywhere from 15 min to 1 hour to fully open. 

How can you attach Green Star Polyps onto the glass?

GSP corals will naturally grow onto the glass on their own if they are placed close enough to spread. But you can easily add a drop of coral glue to a frag and hold it onto the glass for a minute. It will spread from there.


Green Star Polyps are one of those corals that people either love or hate. Although they are very popular, many people don’t like the fact that they grow very fast and can easily cover rocks, glass, and equipment in your tank.

For me, it’s not a problem as these corals are so easy to frag and cut back if you want to. If you are a beginner with keeping corals, you can’t go wrong with GSP. They are the perfect choice.

They will add amazing color to your tank and if you can keep them from spreading onto other corals they are not aggressive.

Knowing how to care for these corals properly will allow them to stay healthy and thrive in any reef tank.