Green Button Polyp

Zoanthus sociatus is a green zoanthid common on the shallow, wave-washed fringing reefs of the Caribbean. Its polyps are about 1 cm across; the oral disc is bright or dark green and the short tentacles are light green. The polyps are connected at the base and form a dense carpet. Because of its easy care and fast growth, it has long been among aquarists' first zoanthids. In the trade it is often sold simply as "green zoanthid"; since color is not enough to identify the species, not every green zoanthid is this species.

Palytoxin warning: Touch colonies with gloves and eye protection, do not put the rock in boiling water and do not scrub it out of the water.

• Moderate to strong light (about 100–250 PAR) and moderate, random flow.
• The middle zone of the rockwork; since it spreads quickly, a separate rock or an area of its own.
• Salinity 1.024–1.026, KH 7–11 dKH; nutrients should be kept under control because hair algae can smother the polyps.

It is photosynthetic; light and normal aquarium feeding are enough. Fine powdered food or zooplankton can be offered occasionally.

It does not sting, but by spreading quickly it can creep in at the base of slow-growing corals. Leave 5–10 cm of clear space from other corals. Some dwarf angelfish, butterflyfish, zoanthid-eating nudibranchs and sea spiders eat the polyps.