Fireworm (large bristle worm) (Eurythoe complanata) care guide

Group
Other invertebrates
Other names
Iridescent fireworm, Orange fireworm, Bristle worm, Fire worm
Family
Amphinomidae
Origin
Warm tropical and subtropical seas worldwide, including the Indo-Pacific, Atlantic and Mediterranean; shallow rock and coral
Water
saltwater
Maximum size
15 cm
Reef safe
no

Care

Eurythoe complanata is a fireworm, a bristle worm of the family Amphinomidae, grey, green or pink with tufts of gills along the body and white bristles down each side. It grows to about 15 cm. It lives under rocks and in coral rubble in warm, shallow seas, and is one of the commonest hitchhikers in reef tanks. How it arrives: hidden in live rock, rubble and the rock bases of coral frags. It hides by day and comes out at night, so many keepers do not know it is there until they see one feeding. Identifying it: a fireworm has flattened segments edged with tufts of white, glassy bristles that flare when it is touched. The many small, pink or reddish bristle worms in most tanks are a different matter: these are harmless or helpful scavengers that eat detritus and leftover food. Problems come from large fireworms, many centimetres long. Sting: the bristles break off in skin and deliver a toxin (complanine) that causes a burning, itching rash. Always wear gloves when handling rock; remove bristles with sticky tape. Harm and removal: large fireworms are carnivores that eat sponges, corals, snails, clams and other worms, and may attack sleeping or weak animals. Remove big ones with long tongs at night or with a bristle-worm trap baited with fish or prawn. Arrow crabs, some wrasses (six-line, melanurus, coris) and dottybacks eat bristle worms. Prevent them by curing and inspecting live rock, dipping or quarantining frags, and not overfeeding, which lets worms multiply. Not livestock: this is a pest and should not be sold as livestock. Small bristle worms are a normal part of a healthy reef and need no action. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most other invertebrates. Never dose them in a tank holding this animal, and read the label of any treatment, fertiliser or algae remover before use. Sources: Wikipedia (en.wikipedia.org/wiki/Eurythoecomplanata). Checked October 2026.

Diet

A carnivore that eats sponges, corals, molluscs, other worms and carrion, swallowing prey by pushing out its lip to four or five times its normal length. In tanks it also scavenges leftover food, which feeds population booms.

Breeding

Reproduces both sexually and asexually, and can regrow from pieces, so cutting one up does not kill it. Numbers rise fast where there is spare food.

Compatibility and tank mates

Not reef safe once large: it can eat corals, clams, snails and sponges and harass weak fish. Predators include arrow crabs, some wrasses and dottybacks. Small bristle worms are harmless detritus eaters.

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

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