Green Star Polyp Coral Care | The Easiest Coral Ever!

If you’re a beginning reef keeper or just looking to keep things simple, you’ll want to go for easy-care corals. And it just so happens we’ve got one for you that fits the bill perfectly! Meet the green star polyp coral, also known as GSP. This species is hardy and tolerant – in fact, it has a tendency to grow a bit too vigorously!

Keep reading for everything you need to know about growing green star polyp coral and how to make sure it doesn’t overgrow your aquarium. 

Green star polyp coral characteristics

Taxonomy

Before we start, a little note. Green star polyps are not necessarily a single species; the name refers to multiple corals in that are similar in terms of appearance and care. In the aquarium hobby, they’ve mostly been referred to as Pachyclavularia, especially P. violacea. The problem is that this genus doesn’t exist, or at least not anymore.

A publication from all the way back in 2001 notes that the corals called Pachyclavularia aren’t a genus of their own at all. Rather, they belong in a different genus called Briareum. As such, Pachyclavularia violacea is actually Briareum violaceum, but for some reason, aquarists haven’t really caught on to this yet!

Does it matter for us aquarists? Not really, although knowing scientific names does help to ensure you’re buying the right thing.

Appearance

Well, the name kind of sums this one up! Green star polyp coral is a soft coral that features eight long tentacles on each polyp. Depending on the exact species and the quality of the coral you buy, the tentacles range from pale to almost fluorescent green. The names ‘violacea‘ and ‘violaceum‘ refer to the purple coloration of the base (calyx) of the polyps.

Wild green star polyps can grow quite tall, but in aquariums, they’re usually mat-forming or encrusting. They grow wide and dense rather than high, usually not reaching more than 2″ but spreading very widely.

Long-tentacled soft corals like the green star polyp make for decorative additions to the aquarium. They sway softly in the flow, and because they’re such vigorous growers, they can actually end up covering entire aquarium panels. Quite beautiful!

Natural habitat

All members of the genus Briareum are naturally found in the Indo-Pacific. Briareum violaceum, specifically, is noted in an overview of the genus to be native to “Vanuatu, Japan (Ryukyu Archipelago, Bonin Islands), Taiwan, Coral Triangle, Australia (Great Barrier Reef)”.

Given that green star polyp corals have zooxanthellae—more about that in the section on diet—they mostly inhabit shallow reefs with plenty of light. They mostly prefer reef flats, lagoons, and the shallower parts of reef slopes, especially if the water is clear.

Green star polyp coral care

If you’re interested in growing a green star polyp coral, you’ll be happy to know that they’re among the least demanding species out there. The genus Briareum makes a great choice for beginners or those setting up a low-tech (nano) aquarium.

Normal reef parameters are recommended, but really, as long as things don’t get too extreme your GSP should be fine. It likes medium to high light levels due to its zooxanthellae, but has been noted to do alright with less light as well.

Water movement should be moderately strong, as this helps keep the coral detritus-free.

Coral control

The biggest problem you’ll likely run into with a green star polyp coral isn’t that it won’t grow well. It’s that it will. The species doesn’t possess stinging tentacles that can bother other corals, but it’s just an incredibly quick grower, and it can form dense mats that choke out its neighbors.

We recommend GSP most strongly for folks who just want to grow a single coral. If you do keep other species, place the green star polyp on a more isolated rock in your aquarium, one that’s at least a few inches away from other objects. You can surround the “island” with more aggressive corals, such as torches, to help keep the green star in its place.

Scrape it off surfaces using a razor blade if need be, or frag it to give away or maybe even sell to your local aquarium store.

Feeding green star polyp coral

Green star polyp corals contain zooxanthellae, photosynthetic algae that help supply them with a source of nutrients. They supplement the coral’s diet using nothing but the light you provide!

That being said, green star polyps do also have the ability to snag floating particles using their tentacles. You can regularly feed your GSP if you want to ensure optimum growth. It’s not a must, especially if you have livestock in the tank that’s fed regularly, but it’s an option.

If you do choose to target feed your green star polyp coral, you can do so using small (thawed) frozen foods like cyclops, rotifers or mysis.

How to frag green star polyp coral

Well… just cut it into pieces and it’ll be fine. Seriously, this is one coral that doesn’t give a darn! If you’d like to multiply yours, just place some pieces of live rock next to the existing colony. It’ll usually quickly grow over the pieces, after which you can separate the polyps in question from the main population. This is done by cutting the stolon, basically the base mat that the polyps grow from.

If you cut pieces that aren’t attached to a small rock or frag plug yet, you can attach them using coral-safe superglue or rubber bands.

Keep in mind that GSP might react by closing its polyps rather dramatically when being disturbed like this. No worries: give your coral some time and it’ll open back up.

Conclusion

A beautiful reef tank filled with corals like the green star polyp coral, gently swaying in the flow, is quite a sight to see. However, even though this species is considered beginner-proof, setting up and maintaining an aquarium is still pretty time-consuming!

The FantaSEA Aquariums team can help by designing, building and maintaining your tank so all you have to do is enjoy it. Contact us with your ideas!