Hard tube coco worm (Protula bispiralis) care guide

Group
Other invertebrates
Other names
Coco worm, Red fanworm, Mopworm, Hard tube feather duster, Double spiral fan worm
Family
Serpulidae
Origin
Recorded off southern Africa (Cape Point to Durban), subtidal from about 25 m; similar coco worms come from the Indo-Pacific
Water
saltwater
Maximum size
18 cm
Temperature
22–26°C
pH
8.1–8.4
Hardness
dKH 8–12, SG 1.023–1.025
Minimum tank
150 litres
Care level
expert
Temperament
peaceful
Reef safe
yes
Flow
Moderate, indirect

Care

The hard tube coco worm is a large serpulid fan worm that lives in a hard, white, chalky tube and spreads two bright spiral crowns of feathery radioles, usually red or pink and white. Wikipedia gives a body of about 6.5 cm in a tube up to 1 cm across; LiveAquaria lists a maximum size of about 18 cm including tube and crown. It lives under boulders, in crevices and on vertical rock faces, and when disturbed it pulls in its crown and seals the tube with a lid (operculum). Name note: Wikipedia records Protula bispiralis only from southern Africa, while aquarium coco worms are usually imported from the Indo-Pacific, so trade animals sold under this name may include other Protula species. Tank set-up: a mature, stable reef tank with a rock and gravel bottom. Wedge the tube into a rock crevice or the gravel, upright, where moderate, indirect flow brings food past without battering the crown. It needs calcium and proper alkalinity for tube growth and is extremely intolerant of poor water quality. LiveAquaria recommends it only for expert aquarists. Water: about 22–26 °C, pH 8.1–8.4, dKH 8–12 and specific gravity 1.023–1.025. Feeding warning: filter feeders like this are hard to keep fed in home aquariums and many slowly starve over weeks or months, even in good reef tanks. Only buy one if you can feed it suitable fine foods every day, and check it is eating before you buy. Copper: copper-based medicines are toxic to shrimp, snails and most invertebrates, and some plant fertilisers carry copper too. Never treat a display tank holding this animal with copper; treat fish in a separate hospital tank, and drip-acclimatise new arrivals slowly. Sources: LiveAquaria (liveaquaria.com/products/hard-tube-coco-worm-expert-only); Wikipedia (en.wikipedia.org/wiki/Protulabispiralis). Checked October 2026.

Diet

Filter feeder: catches microplankton with its crowns. Feed phytoplankton and liquid or very fine organic foods daily, plus fine zooplankton foods such as rotifers and copepods. Turn off pumps briefly and release food upstream of it.

Breeding

Sexes are separate in most serpulids and they spawn into the water; larvae are planktonic. Not bred in aquariums, although tiny related tube worms often spread on their own in reef tanks.

Compatibility and tank mates

Reef safe and peaceful. Angelfish, butterflyfish, some wrasses, hawkfish, hermit crabs and pistol or boxer shrimp may nip the crown. It is harmless to all other animals.

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

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