Green Star Polyps: The Ultimate Guide

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You want a coral for your tank that is beautiful, dynamic, and easy to keep alive and propagate. We’ll explain the reasons that the green star polyp may be the ideal coral to meet your needs.

Whether you’re a beginner reef tank hobbyist or you have lots of experience, you are likely to decide that this is a great coral for you. We’ll also explain how to care for this coral, including tips for propagating and even selling it.

What are Green Star Polyps (GSP)?

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Green star polyps (Pachyclavularia violacea) are a soft coral native to the indo-pacific. They are also known as daisy polyps, star polyps, and starburst polyps.

In case you might be asking yourself, star polyps belong to the octocorallians class. This is a class of corals that have eight tentacles on every polyp. They are in the same family tree as leather corals.

You see, when viewed up close, you will find that each of the polyps looks like an individual little flower. The polyps are attached to the main coral by a rubbery mat called a stolon.

Turns out, these polyps are generally green, but they vary somewhat in the colors available. You can find them in a bright, almost neon green, a darker green with longer tentacles, brown, or a purple-white color.

Best of all, all color varieties are cared for in the same way.

Caring for Green Star Polyps

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In our experience, the green star polyp species is very easy to keep. Their easy care, combined with their beautiful color and movement, makes them one of the most popular corals in the reef hobby.

Simply put, this is an ideal species for the beginner. On the other hand, we’ve found that they can become invasive in a reef tank. You see, they have a rapid growth rate and aren’t too picky about their placement or conditions.

What does this mean for you? These corals are a great option as you are getting started with your reef tank when placed properly. However, they do have some requirements for their environment.

Placement in the Reef Aquarium

Turns out, GSP spread very easily. Care must be taken to place them somewhere that they won’t interfere with other coral species. It is best to place star polyps on a rock that is separate from surfaces where other corals are growing.

In our experience, GSP can easily overwhelm hard corals and purple living rocks. It will grow right over hard, non-aggressive corals and live rock.

You should also avoid placing green star polyps next to aggressive species. Think about it: aggressive Coral will sting star polyps. This stinging keeps the star polyps from looking their best and also will exhaust the aggressive corals since they are constantly defending themselves.

As if that’s not enough, you will likely find that green star polyps spread over the entire tank if given the opportunity. Unless you want your aquarium to be nothing but a mat of green star polyps, it’s best to isolate this species.

On the other hand, propagating a colony of star polyps is very simple. Since they will spread onto whatever surface they have access to, you can simply set rocks near a colony to get a new frag.

Bottom line:

Are green star polyps aggressive?

They aren’t aggressive with stinging, but they do overtake other corals easily

Water Temperature

Green star polyps come from the tropical waters of the indo-pacific. What does this mean for you? It means that star polyps prefer warmer water parameters in your reef aquarium.

In our experience, they need moderate warm water between 72 and 78 degrees Fahrenheit to thrive. But wait, let me tell you something: we’ve found that these corals can survive much cooler temperatures for short periods.

Simply put, this hardiness can be a great advantage for the beginner aquarist who is worried about maintaining proper temperature conditions in the tank.

Water Parameters

By now, you should realize that green star polyps are quite hardy. They are also fairly robust when it comes to their water conditions:

  • Dkh between 8 and 12
  • Water hardness from 8.1 to 8.4
  • Salinity between sg 1.023 to 1.025
  • Calcium In the range of 420 to 500 ppm

Turns out, green star polyps are not as picky about calcium as hard corals. They are not as likely to die out if water hardness or salinity aren’t perfect as many other coral species.

Simply put, you will see their growth slow and they won’t be as likely to reach out fully when water conditions aren’t correct. However, they are unlikely to die unless conditions are extremely unsuitable for a significant period of time.

Water Flow

In case you might be asking yourself, like most corals, this species prefers fairly strong water flow. When water flow is not strong enough, you will notice the tentacles are retracted into the purple mat

On the other hand, when water flow is too strong, green star polyps are prone to restricting their growth and keeping tentacles retracted into the mat. You see, the ideal water flow for star polyps is moderate but not very intense.

Simply put, water flow should be strong enough to move the tentacles around and sweep debris off of the polyps. However, it should not be so strong as to continuously push tentacles in one direction or cause them to retract into the mat.


You see, green star polyps live in shallow water reefs in the wild. Therefore, they prefer bright lighting in your tank as well.

Turns out that green star polyps are zooxanthellae corals. This means that they photosynthesize to create all of their own food.

Without sufficient lights over the tank, they will be unable to photosynthesize and will die.

On the other hand, if you notice lots of algae developing on the mat, lighting may be too bright. If you notice that each green star polyp tends to be coated with algae, it may be that the light is too strong.

In our experience, both fluorescent lighting and LED lighting can be very effective for green star polyps. You may find that you struggle to control temperature with fluorescent lights as they can be hotter.

And the good news? If you are working with a beginner budget, you will likely find that your green star polyps do fine with whatever bright lighting you can afford.

Bottom line:

How much light do green star polyps need?

They need bright light but if it’s too bright you’ll know because they’ll be covered with algae.

How to Feed Green Star Polyps

By now, you should know that green star polyps photosynthesize to create most of their own food. As long as the light is bright enough, they will have all the nutrients that they need.

On the other hand, we’ve found that GSP do best when we feed them supplementally as well.

You see, green star polyps benefit from a weekly diet designed for invertebrates that filter feed. This extra food may not be strictly necessary. However, we’ve found that when feeding fish and other tank inhabitants, green star polyps are quick to catch tiny food particles.

In case you might be asking yourself whether supplemental food is really important, in our experience providing extra particles of food for our green star polyps has resulted in faster growth rates.

And that’s just one side of the story. GSP assists with cleaning the aquarium of excess food because of their filter-feeding.

On the other hand, if you have other corals that need to filter out their food, the green star polyps may end up taking their feed away from them. Therefore, supplemental food is a good idea.

Bottom line:

Do you feed green star polyps?

They don’t technically require food but benefit from filter feeder invertebrate food.

Using GSP for Aquascaping

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Simply put, this beautiful green coral is a popular choice for beginner hobbyists and experienced reef keepers alike when it comes to aquascaping. It has a low growth habit so, not rising much over the mat.

What does this mean for you? This coral works very well as a foreground frag.

Simply put, it is a superb choice to set at the front of the tank in front of other, taller soft coral specimens. Because you can break it into small frag rocks, you can work it into a small site that may otherwise be hard to fill.

This coral has great movement and can be quite engaging. You may find that the polyps close at night or when you are working on the tank and open up again under ideal conditions.

On the other hand, GSP is not a good option for open spots on large pieces of rock. Because it can spread so easily, you may find it overtaking your reef before you even know what has happened.

In our experience, the mat is quite easy to pick up and move. However, this won’t do you any good if it has already smothered coral or purple live rock.

Turns out, one interesting characteristic of green star polyps is their tendency to grow onto aquarium glass. This can be a very useful trait in aquascaping.

If you are struggling to keep an area of glass clean or if you find algae or live rock makes it unsightly, you can simply colonize it with GSP. This coral will look beautiful on the glass and you won’t have to worry about cleaning that area anymore.

Since GSP spreads so readily, aquarium glass is one of the safest places to keep it. You won’t have to worry about it spreading onto other corals or destroying live rock when it is growing on glass.

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

They close at night and if disturbed and open when conditions are right for them.


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We’ve already discussed how green star polyps can propagate rapidly in the aquarium. What does this mean for you? If you want to have more GSP either to spread within the tank, use in another tank, or sell in person or online, this is a very easy coral to propagate.

Here are just a few of the ways to propagate green star polyps:

  • Set a rock next to the green star polyps. The mat will spread easily over the new rock and can be divided into a new frag.
  • Lift the mat off of the host rock. Using a flat tool like a flat head screwdriver, separate the purple mat from the host rock, then peel it away with your fingers. Take the pieces and glue them to a new rock.
  • Grow over rock rubble. An entire purple mat of GSP can be separated from the host rock and laid over rock rubble. You may need to secure it with glue or fishing line in a couple of places. Soon the mat will attach to the rock pieces so you can divide it

Buying Green Star Polyps

Turns out, this coral is very popular for use in the reef tank, but this doesn’t mean it is necessarily cheap. You can expect to pay around $50 for a typical frag. And that’s just one side of the story… some color variations will cost more than others.

However, in our experience, this coral is fairly readily available. You will be able to find it in most aquarium stores or online.

Selling Green Star Polyps

Think about it: Because this coral is quite easy to propagate and sells at a reasonable price, it is a popular choice for propagating and selling. You may be able to sell it online, back to your local thrift shop, or trade-in frags for other corals for your reef tank.

No wonder this may also be a good option for selling or trading within hobby groups. You are likely to find more success in selling less readily available color options.

Best of all, since all color morphs are equally easy to grow and propagate, it may be worth paying a bit more to invest in a rare color that you can sell for more down the road.

Enjoy the Green Star Polyp

Simply put, if you are looking for a beautiful green coral with excellent movement that is easy to grow, this might be the one for you. It does well under a variety of water conditions as long as it has enough light. Under superb conditions, it is extremely easy to propagate and is a lovely addition to your tank.

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