Giant zoanthid (Zoanthus gigantus) care guide

Group
Corals
Other names
Giant zoa, Large-polyp zoanthid
Family
Zoanthidae
Origin
North-west Pacific, described from southern Japan
Water
saltwater
Temperature
22–26°C
pH
8.1–8.4
Hardness
dKH 8–12
Care level
beginner
Reef safe
yes
Lighting
Low to moderate; about PAR 80–150
Flow
Moderate, indirect

Care

Zoanthus gigantus is a large-polyped zoanthid, described from southern Japan, with polyps bigger than most Zoanthus. Like other zoanthids it forms colonies of button-shaped polyps joined at the base, and colours range from greens and browns to brighter morphs. It is not sold by name at LiveAquaria or Top Shelf Aquatics; the care below draws on their general Zoanthus listings (colony polyps, Zoanthus sp.; Top Shelf's Bowzer zoanthids). Placement: low to middle of the rockwork, ideally on an isolated rock so the colony cannot spread onto other corals. Top Shelf Aquatics gives low to moderate light (about PAR 80–150) and moderate, indirect flow that keeps the polyps gently moving and detritus off the mat. Acclimatise to light over 2–3 weeks. Water: about 22–26 °C, pH 8.1–8.4, dKH 8–12, with some nitrate and phosphate present rather than none. Iodine and trace elements support colour. Growth is usually fast. Safety: zoanthids and palythoa contain palytoxin, a dangerous toxin. Wear gloves and eye protection when handling or fragging them, and never boil or scrub rock carrying them. Zoanthids are not CITES-listed. Sources: LiveAquaria (liveaquaria.com/products/colony-polyp-zoanthus-corals); Top Shelf Aquatics (topshelfaquatics.com/pages/corals/bowzer-zoanthids-coral). Checked October 2026.

Diet

Mainly photosynthetic. It can be fed fine foods (zooplankton, phytoplankton, rotifers, powdered coral food) once or twice a week, with pumps off briefly.

Breeding

Easy. Cut through the mat between polyps with a scalpel or scissors and glue small clumps to plugs with gel superglue. Wear gloves and eye protection because of palytoxin.

Compatibility and tank mates

Semi-aggressive: short sweeper tentacles and fast spread let it overgrow neighbours, so allow 5–10 cm. Watch for zoanthid-eating nudibranchs, sundial snails and spider crabs.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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