Briareum

Briareum, better known as Green Star Polyps (GSP), is one of the most popular and recognisable beginner corals in the reef hobby. It forms a distinctive purple mat from which bright green star-shaped polyps emerge, creating a stunning living carpet. Often mislabelled as Clavularia viridis in the trade, GSP is actually Briareum. Place them under moderate PAR (75–200 PAR) with moderate flow — they are remarkably adaptable and will grow in almost any position in the tank. Standard reef parameters suit them well: alkalinity 7.5–9 dKH, calcium 400–440 ppm, and temperature 25–27°C.

The primary consideration with GSP is managing their aggressive growth. They are one of the fastest-growing corals in the hobby and will encrust over any surface they contact — rockwork, glass, equipment, and even other corals. Many Australian reefers use this to their advantage by letting GSP cover the back wall of their tank, creating a vibrant green living backdrop. To prevent unwanted spread, place GSP on isolated rock islands surrounded by sand, or on removable structures. Prune regularly by peeling back the mat where it is not wanted.

Fragging GSP is effortless — simply peel or cut sections of the mat and attach to frag plugs or rock with superglue. They establish rapidly and begin spreading within days. GSP close their polyps when disturbed or when water quality dips, making them a useful visual indicator of tank conditions. They are among the cheapest and most widely available corals from Australian retailers and frag swaps. For new reefers, GSP offer instant gratification with their fast growth and vivid colour.