Invertebrates
beginnerBristle worms in a reef tank: good, bad and fireworms
Polychaeta (many families; fireworms are Amphinomidae) · Annelida (segmented worms)
Also called: bristleworm, fireworm, fire worm, polychaete, Hermodice carunculata, bearded fireworm
Checked against 3 sources on · reefcalcs editorial
Quick reference
Care level
Beginner
Adult size
Varies by species; the bearded fireworm reaches nearly a foot[2]
Lifespan
Varies by species; no reliable source
Diet
Most: detritus, bacteria, algae, small crustaceans and other worms; Hermodice: corals, urchins, snails, sponges[1, 2]
Tank size
Not applicable: they arrive on live rock and live in the rock and sand.
Temperature
76–81 °F (general reef range)
Salinity
35 ppt (SG 1.0264 at 25 °C)
pH
8.0–8.4
What are bristle worms?
"Bristle worm" covers a huge range of polychaete worms. Reefs.com describes most as scavengers and opportunistic predators of other worms, detritus, bacteria, algae and micro-crustaceans, which is to say part of the clean-up crew, and estimates that about 99 % are harmless and reef safe.[1]
The worms with a bad name are fireworms, family Amphinomidae.[1] The bearded fireworm, Hermodice carunculata, grows to nearly a foot, is orange to purplish-grey with tufts of white bristles and reddish gills on every segment, and counts corals as a significant part of its diet, along with urchins, snails and sponges.[2] Reefs.com notes it's rare in aquaria; it can arrive on Caribbean corals.[1, 2]
Feeding
They need no feeding: they live on detritus, leftover food, algae and small animals.[1] Like any scavenger, their numbers rise with the food supply, so a swarm at feeding time usually means there is more food and detritus than the tank needs.
Aggression and spacing
Reefs.com says that some aggressive or oversized worms may attack clams, anemones, corals and even fish, and that such worms should be removed.[1] Hermodice is nocturnal and hides deep in crevices, so the first sign is often corals or invertebrates going missing.[2]
Tankmates
Arrow crabs eat smaller bristle worms.[3] For Hermodice, Reefs.com says biological control is limited: certain wrasses show some interest, and the crown cone snails that prey on it are dangerous to keep.[2]
Safety
Don't handle them. Reefs.com warns that large worms' sharp teeth and bristles can puncture skin,[1] and that fireworm bristles are hollow and carry toxins that cause burning pain and irritation, and in severe cases nausea.[2] Its suggested first aid is to lift the bristles out with adhesive tape, then apply hot water, vinegar or rubbing alcohol;[2] get medical help for a severe reaction.
Troubleshooting
Dozens of worms swarm when food goes in
Likely cause: Plenty of food for scavengers: leftovers and detritus.
Fix: Feed less and siphon detritus; trap the largest worms.[1]
A large orange worm with white tufts near a damaged coral
Common mistakes
Bristle worms FAQ
- Are bristle worms bad for a reef tank?
- Usually not: Reefs.com estimates about 99 % are harmless scavengers. The exceptions are mainly fireworms (Amphinomidae) such as Hermodice carunculata.[1]
- How do I get rid of bristle worms?
- Feed less, and trap large ones with a piece of shrimp as bait or pull them off rock with tweezers.[1]
- What's the difference between a bristle worm and a fireworm?
- Fireworms are the stinging Amphinomidae; the bearded fireworm grows to nearly a foot and eats corals.[1, 2]
- What eats bristle worms?
- Arrow crabs eat smaller ones;[3] some wrasses show interest in fireworms.[2]
- What do I do if a bristle worm stings me?
- Reefs.com suggests removing the bristles with tape, then hot water, vinegar or rubbing alcohol.[2] Get medical help if the reaction is severe.
Sources
- Reefs.com — Bristle worm (pest profile)
- Reefs.com — The bearded fireworm, Hermodice carunculata (citing Witman 1988, Wolf et al. 2014, Verdes et al. 2018 and others)
- LiveAquaria — Arrow crab (eats smaller bristle worms)
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