Green star polyps care

Quick reference

What are green star polyps?

Briareum violaceum is an Indo-Pacific octocoral recorded from Japan and Taiwan through the Coral Triangle to the Great Barrier Reef. Like the rest of its genus it hosts zooxanthellae, so it lives in shallow, well-lit water.^[3] In aquariums it grows as an encrusting mat of purple tissue with fluorescent green polyps that spreads quickly over rock and glass.^{[1, 2]}

Lighting for green star polyps

Wide tolerance. Whitecorals says weak to stronger lighting, and FantaSEA says medium to high, adding that it does fine with less.^{[1, 2]} We found no reliable PAR figure.

Flow and placement

Moderately strong flow keeps detritus off the mat,^[2] and it tolerates strong currents.^[1]

Feeding

Mostly fed by its zooxanthellae; target feeding with small frozen foods such as cyclops, rotifers or mysis is optional.^[2] It does well with somewhat higher nutrients.^[1]

Aggression and spacing

It has no stinging tentacles that bother other corals; the problem is overgrowth. It forms dense mats that can smother neighbours and cover whole aquarium panels.^[2] Its genus is rich in briarane compounds, but we found no evidence it chemically harms other corals in tanks.^[3]

Tankmates

The nudibranch Phyllodesmium briareum feeds on briareid soft corals in the wild and has been reported from this species,^[6] though we found no report of it as an aquarium pest. No reliable source names fish that nip GSP.

Fragging and propagation

Cut through the base mat (stolon), or set a rock against the colony, let it grow over and cut it free; attach pieces with coral-safe superglue or rubber bands. Unwanted growth scrapes off with a razor blade.^[2]

Troubleshooting

Common mistakes

• •Putting it on the main rockwork next to other corals.^[2]
• •Letting it reach the glass.^[2]
• •Assuming it's dead when the polyps stay closed for days after a move.^{[1, 2]}
• •Low flow that lets detritus settle on the mat.^[2]

Equipment & food for this species

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Soft corals don't strictly need feeding. Reef Roids help if you want faster growth.

Green star polyps FAQ

Why is my GSP not opening?

Most often it's stress from being moved, fragged or disturbed; it can stay closed for several days, sometimes about two weeks. Test the water if it followed a change.^{[1, 2]}

Is green star polyp invasive?

In a tank it spreads quickly as a mat that can smother neighbours and cover the glass, so keep it on an isolated rock.^[2]

Does green star polyp sting other corals?

No. It lacks stinging tentacles that bother other corals; the risk is overgrowth.^[2]

How do you frag GSP?

Cut the base mat, or let it grow onto a rock placed next to it and cut it free; attach pieces with coral-safe superglue or rubber bands.^[2]

Does GSP need to be fed?

Not necessarily. It's mainly photosynthetic; small frozen foods are optional.^[2]

Is green star polyp Pachyclavularia or Briareum?

Pachyclavularia was merged into Briareum, so the accepted name is Briareum violaceum.^{[3, 4]} Whether every 'GSP' sold is that species is unconfirmed.^[5]