Christmas tree worm (Spirobranchus giganteus) care guide

Group
Other invertebrates
Other names
Christmas tree worm rock, Christmas tree coral (Porites with worms)
Family
Serpulidae
Origin
Tropical coral reefs from the Caribbean to the Indo-Pacific
Water
saltwater
Maximum size
4 cm
Temperature
22–26°C
pH
8.1–8.4
Hardness
dKH 8–12, SG 1.023–1.025
Care level
intermediate
Temperament
peaceful
Reef safe
yes
Flow
Moderate, alternating flow to bring food

Care

The Christmas tree worm is a small tube-dwelling fan worm whose two spiral crowns of feathery tentacles look like tiny, brightly coloured Christmas trees; crowns come in red, orange, yellow, blue, white and many other colours. The worm itself is about 4 cm long and lives in a hard chalky tube up to 20 cm long, buried in living coral. When disturbed it snaps back into its tube in an instant and plugs the entrance with a spiny trapdoor (operculum). On the reef it is usually embedded in massive corals, especially Porites and brain corals, settling as a larva on live coral that then grows around its tube. In the trade it is nearly always sold as a 'Christmas tree rock': a piece of Porites coral holding several worms. Keeping it therefore means keeping that coral alive. Porites is a stony coral that needs bright reef lighting, stable calcium and alkalinity and good water quality; when the coral dies, the worms are exposed and usually die too. Place the rock in good light with moderate, varied water flow. The worms are filter feeders and, like other fan worms, they are hard to keep fed in clean, heavily skimmed tanks and often decline slowly. Target-feed or broadcast fine foods regularly. Copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most invertebrates. Sources: Wikipedia (en.wikipedia.org/wiki/Spirobranchusgiganteus). Checked October 2026.

Diet

A filter feeder: the hair-covered crowns trap plankton and fine particles and pass them to the mouth, and also serve as gills. Feed liquid phytoplankton, rotifers, copepods and very fine particulate foods a few times a week, turning off strong pumps briefly or spraying gently near the rock. The host Porites coral also benefits from these foods.

Breeding

Sexes are separate. Adults release eggs and sperm into the water, and the larvae settle on coral heads and burrow in. They are not bred in aquaria.

Compatibility and tank mates

Reef safe and harmless to everything. Fish that pick at invertebrates, such as many angelfish, butterflyfish, puffers, triggers and some wrasses and hawkfish, may nip the crowns until the worms stop opening. Some crabs and shrimp also pick at them.

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

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