Sea Mat Zoa (Zoanthus sociatus) Care Guide
Zoanthus sociatus is a hardy encrusting zoanthid forming dense, colourful polyp mats, popular but a producer of toxic palytoxin.
Compiled by Aquairi from published sources · Published · Updated
Overview
Zoanthus sociatus is a colonial zoanthid in the family Zoanthidae, known in the hobby as sea mat or zoas. It forms dense encrusting mats that can completely cover rock with brightly coloured circular polyps. The genus contains fluorescent-protein pigments, and many colour morphs of this species are available in the trade.
Taxonomy
- Family: Zoanthidae
- Order: Zoantharia
- Class: Hexacorallia
- Scientific name: Zoanthus sociatus
Habitat
Zoanthids occur on shallow reefs in the Caribbean and Indo-Pacific, where they encrust hard substrate. They are hardy and well suited to mature reef aquaria as a beginner coral.
Tank requirements
- Temperature: 24-26 C (75-79 F)
- pH: 8.1-8.4
- Carbonate hardness (KH): 8-11 dKH
- Calcium: 380-450 ppm
- Magnesium: 1280-1350 ppm
- Specific gravity: 1.024-1.026
- Lighting: ~50-150 PAR (medium)
- Flow: low
- Minimum tank maturity: 3 months
Feeding
The coral is photosynthetic, deriving most of its energy from symbiotic zooxanthellae. It can also capture fine particulate foods, and supplemental amino acids or reef coral foods may support colour and growth.
Compatibility
It is passive and reef-safe, compatible with fish and shrimp. As a fast-spreading mat coral it should be given its own rock to limit overgrowth of neighbours.
Zoanthus sociatus (Sea Mat) Propagation Guide
Overview
Zoanthus sociatus, the green sea mat or button polyp, is a zoanthid in the order Zoantharia. It forms piecemeal mats of green to turquoise polyps connected by stolons, with each polyp bearing about 30 short tentacles that stay extended day and night. It occurs in shallow reef zones from the Caribbean to southeastern Brazil.
Reproductive Mode
Zoanthus sociatus reproduces primarily asexually through budding and fission, with sexual reproduction occurring seasonally; colonies become reproductive only once they reach a certain size and use external fertilization.
Fragging / Asexual Propagation
Aquarium fragging mirrors the natural budding of the mat. Using a razor blade, slice the tissue of the connecting mat around the polyps to be removed, then trace the cut with coral cutters so the section breaks free. The piece is glued onto a clean, dried frag plug, and a baster is used to blow off secreted mucus. Polyps that detach without substrate can be placed on chunky sand in low flow, where they will encrust.
Sexual Reproduction
In the wild, mature colonies reproduce sexually by releasing gametes for external fertilization once they exceed a threshold size. This is seasonal and not the route used for aquarium propagation, which relies on cutting the mat.
Conditions for Propagation
The polyps obtain nearly half their energy from symbiotic zooxanthellae, with the remainder from heterotrophic feeding. Fresh frags settle best in low flow under the lighting and water parameters recorded for this species in the knowledge base.
Common Challenges
The main hazard is palytoxin, one of the most poisonous non-protein substances known, which Zoanthus species carry. Exposure can occur through skin contact, the eyes, and inhalation of aerosols when the polyps are disturbed; documented aquarium cases include severe respiratory illness after scraping zoanthids and hospitalizations after coral removal.