How to Grow and Care for Green Star Polyps

Alison Page

Alison Page


How to Grow and Care for Green Star Polyps

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If you’re a beginner to the reef aquarium hobby, Green Star polyps are a great starting point and can add color and movement to your setup. These corals attach to rocks and other hard surfaces, resembling a beautiful field of waving phosphorescent grass once the colony is established.

In this guide, we give you all the information that you need to give your Green Star polyps the very best care.

Green Star Polyps

What is Green Star Polyps?

The Green Star polyp, scientific name, Pachyclavularia violacea, is a soft coral species that can be seen growing profusely in the shallow tropical waters of the Indo-Pacific up to depths of around 62 feet, where they inhabit rubble areas of lagoons and reefs.

At one time, Green Star polyps were thought to be Clavularia Viridis, but that is not correct. These organisms are octocorallians; that is, they belong to the subclass of corals that have eight tentacles on each polyp. Green Star polyps are part of the Alcyonacea order, which sets them in the same coral family as the leather corals.

Each of the polyp’s tentacles has a serrated appearance, earning them the common names, Daisy polyp, and Green Star polyp. The polyps are attached to each other via a thick purple, rubbery mat known as a stolon.

Star polyps are rapid growers and will readily colonize any hard surface in your aquarium, including other species of coral and live rock.

The polyps have eight feathery, retractable tentacles and are bright fluorescent green with a band of yellow or white around the outside of the central oral disc. Green Star polyps can reach up to two inches in diameter, which is quite sizeable in comparison to other related coral species.

Other common names for this species of coral include Daisy polyps, Starburst polyps, and Purple Mat polyps.


When you’re searching for Green Star polyps, you will notice that there are a few colors available.

  • Metallic green (fluorescent neon)
  • Wintergreen (dark green color with long, flowing tentacles)
  • Brown
  • Purplish white

The care requirements for these variants remain the same. So, pick a color that you really like and which will provide the best effect for your tank.

How to Grow and Care for Green Star Polyps

Care of Green Star polyps

This species of coral is perfect for a beginner to add to their reef aquarium. Here’s how to care for this stunning, living gem.

Tank conditions

Although the Green Star is considered to be a peaceful coral, you should place your specimen carefully so that you can manage its growth. This species grows extremely quickly and will quickly overtake a reef tank if not carefully managed.

We recommend placing Green Star polyps on small islets of rock so that the coral cannot spread out of control.

Keep your Green Star polyps well away from hard corals and living rocks to prevent them from becoming colonized. Also, don’t put Green Star next to soft corals that have stinging nematocysts, which will sting their neighbor. That will slow the Green Star’s growth rate by causing them to remain retracted. Also, the offender will suffer slower growth, as it is putting all its energy into defending itself from its neighbor.

The bottom line is to allow all your corals plenty of room for growth!

Water parameters

Green Star polyps originate in the tropical ocean waters of the Indo-Pacific and Fiji, meaning that they need a water temperature of between 720 and 780 Fahrenheit to thrive.

dKH should be between 8 and 12, water hardness 8.1 to 8.4 pH, and salinity sg 1.023 to 1.025. Calcium levels in the water should be maintained at between 420 to 500 ppm.

The water flow around the habitat should be fairly strong to keep the Green Star’s mat clean and healthy.

Green Star Polyps grow by spreading a purple mat that encrusts all nearby hard surfaces, including hard corals and living rock. If you notice that your Green Star is not growing as quickly as it once did, it’s likely that the pH and alkalinity of the water are slightly out.

Also, if the polyps remain retracted into the purple mat regardless of whether the lights in the tank are on or off, it could be that you don’t have sufficient water flow through the mats. Try lifting the coral and briefly placing it in front of the filter powerhead to blow away any debris that’s collected on the mat. You can also clean the mat with a soft toothbrush.

However, it’s best to place your polyp mats in an area of the tank where they will receive moderate, rather than high water flow, which could cause the polyps to retract.

Providing your corals with these conditions should see optimal growth.


These are shallow-water organisms, preferring moderate to high lighting levels. If the light level is too low, the coral won’t be able to photosynthesize and will eventually die.

Diet and nutrition

Green Star polyps obtain most of their nutritional requirements through photosynthesis facilitated by the zooxanthellae that the coral contains within its body. That means that these organisms can take all the food they need from the lighting in your tank.

That said, the corals will also benefit from a weekly feed of nutritional products that are specifically formulated for filter-feeding invertebrates. Although that’s not strictly necessary, you may notice when feeding your fish that the Green Star polyps will trap tiny particles of food in their tentacles, so a little extra will certainly go down well.


The propagation of Green Star polyps is very simple. All you need to do is peel small frags of the purple mat from one rock and use super glue to attach each frag to another rock or suitable surface.

Slide a flathead screwdriver between the mat and the rock to carefully lift the mat, and then slowly peel the coral away from the rock with your fingers. Once you’ve freed a couple of pieces of the mat, place a few small blobs of super glue on the new site and stick the frag to it. The coral will be fine out of the water for a few minutes. Once the glue has dried, replace the rock with its coral frag back into the tank.

After a few days, you should see the full polyp extension.


Green Star polyps are popular, but they are still quite pricey, selling for anywhere between $30 and $60 for a frag. As this coral is so easy to propagate, you may have luck selling a frag or two to your local reef shop or trading them for store credit.

The demand for these corals is always steady, so availability is good. If you don’t have a stockist near to your location, email one of the many online reef specialist stores and order some frags online.


To keep you well-informed, here are a few of the most commonly asked questions about Green Star Polyps, together with our answers.

Q: Do green star polyps need calcium?

A: Green Star polyps should be kept in an environment where the calcium levels in the water are between 420 and 500.

Q: How long does it take for Green Stars to open?

A: Although these corals are great for beginners, they are quite fussy about water flow, lighting, and correct placement too. Until conditions are to their liking, it can be a few days before the polyps open up. You may well find that the polyps retract when you turn the lights out in the aquarium, emerging again when “daylight” returns.

Q: What food do Green Star polyps need?

A: These soft corals make their food through photosynthesis, deriving everything they need from the light in the tank. In the wild, the polyps live on shallow reefs and lagoons where they get plenty of natural light, and you can replicate that through the lighting in your tank.

You can also feed the polyps once a week with food that’s specially formulated for invertebrates.

Q: Do green star polyps shed?

A: Sometimes, Green Star polyps “sulk.” That usually happens when the water flow is inadequate or other conditions on the reef are not to their liking. You may notice that many polyps shed some slime to remove any algae that may be growing on them. Once the algae have gone, the polyps will reopen.

In summary

Green Star polyps make a great starter coral for many beginner reef tank hobbyists.

This coral species is easy to keep and has relatively low maintenance requirements, provided that you ensure that your tank has the good water flow and the lighting conditions that the polyps like.

Green Stars are very prolific and will spread throughout your setup. So, you may like to take a surplus frag or two to trade at your local marine store or to give to your friends and fellow reef enthusiasts.

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