Green Star Polyp Care – A Complete Guide

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When it comes to Green Star Polyp Care, there usually isn’t much to it. The main thing is learning how fast it grows, where to place it, and how to control it. It can grow quite large if given the right conditions and some reefers have event used them to create a wall of corals!

Today’s post is all about the Green Star Poly. Come find out all there is to know about this beautiful creature with our complete guide on how best to take care of your Green Star Polyp. You’ll be glad you did!

Species Overview

Scientific NameBriareum spp. (widely Pachyclavularia violacea)
Common NamesGreen star polyps (GSP), daisy corals, starburst corals, star corals
OriginWidely found throughout the Indo-Pacific1
Common ColorsGreens, yellows, and browns with purple skeleton
Care LevelEasy
LightingModerate-High (50-200+ PAR)
Tank PlacementBottom, Middle, Top
Flow RateModerate-High
Temperature Range76-82 degrees F
pH Range8.0 – 8.4
Salinity1.025 or 35 PPT
Alkalinity8 – 12 dKH
Calcium Level350 – 450 PPM
Magnesium Level1250 – 1350 PPM

Origins And Habitat

Like many other corals, green star polyps come from the warm waters of the Indo-Pacific in turbid lagoons and along shallow to moderately deep reefs. There, they can be found alongside other soft corals, such as Xenia spp. and Clavularia spp..

Green star polyps are soft corals, meaning they do not have a calcium carbonate skeleton. Instead, they quickly grow as encrusting mats over rocks and other sessile objects.


In general, green star polyps are taxonomically categorized as Pachyclavularia violacea. This is a very broad name for these corals though, and it’s very likely that you have a species that is something other than Pachyclavularia violacea. The Pachyclavularia genus is also synonymous with Briareum and the two can be used interchangeably for this species.

Green star polyps are a type of soft coral (Alcyonacea order) though they contain sclerites, or small pieces of skeleton, within their tissue for structure.

What Do They Look Like?

Green Star Polyp

When fully spread, green star polyps look like a lawn of grass. Individually, they have a white center and eight radial green tentacles. These serrated-like tentacles come out from a purple base with tubes for every polyp.

When closed, this coral looks like a pointy, purple mat. As we’ll discuss later, these corals can sometimes be temperamental and may be closed for extended periods of time if something is unfavorable in the tank.


There are not many variations of green star polyp and their appearance largely depends on the type of aquarium light being used. Because they are so easy to grow, they are mostly aquacultured.

There are a few varieties of green star polyp though, mainly with differences between shades of green, tentacle length, and skeleton branching.

It is very common to come across ‘neon’ varieties of green star polyps where the tentacles are fluorescent green. Other variations might have a more defined white center or more tints of yellow, though the general purple and green coloration stays the same.

Some variations of green star polyp might also be long-tentacled. It is believed that long green star polyps are hardier and grow faster than shorter ones, which can sometimes be confused with galaxea corals (Galaxea fascicularis).

Within the aquarium, there is also said to be a branching variety of green star polyp. This variety is different from the regular encrusting type and is much more rare and desirable. The problem is that it can be very difficult to tell apart from others as there is little difference between small frags and usually no difference at all between namings.

Branching green star polyps grow outwards, away from the rock; this means that they don’t necessarily need to grow on top of rock to spread and can create archways and limbs that extend across the reef tank.

Still, green star polyps have not reached the brand-name-worthiness of other soft corals, which keeps their prices relatively low.

Galaxea spp.

To the untrained eye, green star polyps can look very similar to species of Galaxea coral. This can be a costly mistake as Galaxea have long sweeper tentacles that can severely damage other corals.

These two corals look very similar and even have similar care requirements. Overall though, green star polyps tend to be larger, less compact, and have more tapered tips. In a mat, galaxea corals can have a shaggy appearance whereas green star polyps will have a more uniform sway.

Green Star Polyp Care Guide

Green Star Polyp Close Up

Green star polyps are one of the most versatile corals in the aquarium, meaning they can be placed almost anywhere. The problem is that they will also spread everywhere they can.

Green star polyps do best under moderate to high reef lighting with moderate to high flow; they can usually withstand conditions above and below this, though low light will result in slower or minimal growth and high light can cause bleaching and algae.

These corals need moderate to high flow in order to keep algae off their purple skeleton. Because green star polyps are so concentrated, water flow needs to be able to remove any waste or debris from the top of the coral.

If water flow is inadequate, algae can start to build over the opening of the tubes, which prevents the polyps from expanding. Even more so, snails, hermit crabs, and algae-loving fish might start to crawl over or pick at this algae which can result in longer periods of retraction.

However, you also want to make sure that you don’t place your green star polyps too close to other corals. These corals grow extremely fast and won’t hesitate to grow over and shade out zoanthids or other peaceful corals.

Because of this, many hobbyists like to keep them on a rock island of their own as they will rarely grow onto the substrate. Another option is to keep them around much more aggressive coral species (like LPS corals) that should fight back any green star polyps that try to invade their space.

Another popular option for green star polyp placement is the back or the bottom of the reef tank. Many hobbyists choose to create a background of green star polyp or a lawn on a bare bottom setup. It only takes a small piece of frag to have a waving mat of green within a couple of months.

Temperament In The Aquarium

Green star polyps will not sting other corals and are very peaceful. However, they are highly invasive and will not hesitate to grow over and shade out other corals.

As mentioned before, these corals do best when isolated. You do not need to worry about other corals being stung by them, but rather taken over by them. As long as green star polyps are kept away from other, less aggressive corals, then they should stay manageable.

Though these corals aren’t known to have a powerful sting, it is still recommended to keep them away from other corals at all times to prevent aggression.

Are They Toxic?

There is some belief that green star polyps are toxic and can release damaging chemicals into the aquarium when stressed, like zoanthids. However, this is largely a myth and has yet to be proven within the hobby.

If you are concerned about green star polyps releasing toxins, use gloves when handling and run activated carbon. Otherwise, it is extremely rare, if not impossible, to have any toxin complications due to green star polyps.

Care And Maintenance

Green star polyps are one of the easiest corals to care for, though some hobbyists can have difficulty with them due to the reef tank being too clean, inadequate flow, or extreme lighting.

Otherwise, green star polyp maintenance and upkeep are straightforward.


Like other corals, green star polyps need available nutrients in the water column. They need nitrates, phosphates, magnesium, calcium, and a stable alkalinity for healthy growth and vibrant colors.

That being said, these soft corals do not need additional nutrients to be dosed other than what is introduced through feedings and fish waste. In fact, many hobbyists look to slow down green star polyp growth rather than speed it up.


Many hobbyists choose not to feed their green star polyps as they get the majority of their food through photosynthesis, but they’ll definitely enjoy some supplemented foods every now and then.

For best results, use a powder or liquid food, like zooplankton; these corals are not able to take in larger foods through their mouths.

Trimming And Algae

Green star polyps grow fast, and eventually, you will need to control that growth. Some hobbyists choose to frag these trimmings, though the supply might outweigh the demand.

These corals can be difficult to completely remove from a surface and will often grow back after some time. When you see green star polyps growing somewhere you don’t want them, simply scrape them off and dispose of them. Make sure you get all the pieces as they can reseed themselves elsewhere in the tank.

Another way to combat green star polyp growth is by shading it out with a larger object. This can affect other corals too if not carefully placed, but it is an effective way to deprive the coral of necessary light for growth.

At the same time, you will want to look out for algae growing on the mat of the coral. It is recommended to use a turkey baster weekly to gently remove any algae or debris that might be caught. If you notice that your green star polyps have been closed more than usual lately, it could be bothersome algae.

What Are Good Tankmates?

Tank Raised Clownfish

Green star polyps can be kept with nearly everything, including not reef-safe species. Here’s how.

In theory, green star polyps can be kept with anything from clownfish and tangs to triggers and angels. This is due to the fact that this coral grows so incredibly fast. There is still the very real possibility that not reef-safe fish will eat green star polyps, but these corals are very likely to bounce right back and make up for what had been lost.

It should also be noted that green star polyps might not look as appetizing as other fleshy large polyp stony (LPS) corals, so some coral-hungry fish might leave it alone. If you find yourself with a fish that eats everything you put into the tank but you’re still determined to have corals, then get an inexpensive frag of green star polyps and try your luck.


It should come as no surprise that green star polyps are incredibly easy to frag. The hardest part will be separating the pieces from the rock.

In order to frag green star polyps, first, find a manageable side of the rock where the mat will be easy to separate. If you can’t find a good place to cut, then choose the best spot and use a scissor, scalpel, or razor blade to cut through and detach the piece from the rock.

For the most part, it doesn’t matter how big or small of a piece you frag as it will quickly recover and start growing. Simply attach the frag to a frag plug with superglue (cyanoacrylate). You may dip this frag in iodine or a special coral mix, but this is not necessary.

Place the frag towards the bottom of the reef tank. The polyps should start to open in a few days, though these corals can be temperamental after handling. Do not worry as they can survive a couple of weeks of being retracted.

As mentioned before, your green star polyps may grow too quickly for how much fragging you can manage. These excess corals can be moved to the sump to help with nutrient exportation, given to another hobbyist, or disposed of correctly. If you want a video tutorial, you can check out the video below by OceanStateAquaticsTV.

How Long Does It Take For Them To Spread?

Green star polyps can cover a rock in a matter of months. Growth may be slow initially and your coral might not even open for a few days when you first introduce it into the reef tank.

If conditions are right though, you will have new growth almost every day. This can be seen on the edges of the mat, where the flesh is light purple or white instead of the dark reddish-purple of the rest of the colony.

If you find that your green star polyps aren’t opening, try to keep conditions stable. You will want to move them around to new areas of the tank for better flow or lighting, but it is best to leave them where they are until they open. If you see algae starting to grow on top of the mat, gently waft away or turkey baster the algae off.

At the same time, make sure there are available nutrients in the water column. It is not unheard of for green star polyps to not open when sufficient nutrients aren’t available.

Closing Thoughts

Green star polyps are one of the best corals and one of the worst corals. They offer vibrant colors and exciting movement to all levels of the aquarium, but they can easily outcompete other species and be extremely difficult to remove once introduced to the tank.

They are one of the best beginner corals due to their resilience and relatively low care requirements, but can also make a beautiful backdrop or lawn for more intricate setups.

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