Bristleworms: Friend or Pest?

Bristleworms: Friend or Pest?

If you’ve ever looked in your saltwater tank and wondered “what is that ugly spiky looking thing on the sand bed?”, that’s a bristleworm. Just about every saltwater or reef tank has them whether you see them or not. Try looking at night with a flashlight and you are more likely to find your bristleworm inhabitants. But what are bristleworms, and should you eradicate them with extreme prejudice?

 What are bristleworms?

Bristleworms (or bristle worms), are a type of segmented marine worm that can grow up to a staggering 2 feet. Fortunately, the bristleworms you see in your saltwater tank will be under 6 inches. Each body segment is covered in bristly tufts which is where they get their name. Depending on the species these tufts can be sharp and even painful so don’t grab one with your bare hands. Fireworms, (a type of bristleworm) are known to have sharp bristles, if you see an exceptionally long or fat bristleworm it’s possible or even likely that it is the dreaded fireworm.


What do I do about my bristleworms?

The answer to this is totally up to you. Bristleworms are generally perceived as ugly, creepy, or “the stuff nightmares are made of”. I heard that last one somewhere, I can’t remember where. Despite their off-putting look, bristleworms can be quite beneficial to your reef or fowler tank. They will scour the rocks and sandbed looking for food. Uneaten fish food, detritus, and even the body of a sadly departed fish will be food for bristleworms. The cleanup crew qualities of the bristleworm cannot be overlooked, but it can be replaced with other cleanup animals that maybe look less creepy. So, if you are willing to put up with them for the sake of the ecosystem you are welcome to. If you are not, I wouldn’t be surprised, there are numerous different ways to get rid of bristleworms.


Getting rid of bristleworms

The first and most obvious idea is pulling them out yourself. Please wear gloves and use tweezers or small tongs. You will almost certainly not get them all doing it this way, but it will probably make you feel better.

The best way is to utilize another animal that hunts and eats bristleworms, like the coral banded shrimp.

 Other invertebrates and fish that will eat bristleworms inlcude:

    1. Arrow Crab (may attack small fish if food is lacking)
    2. Coral banded shrimp
    3. Six line wrasse (the sixline wrasse a favorite of mine for it's many jobs)
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  1. Yellow coris wrasse
  2. Melanurus wrasse
  3. Sunset wrasse
  4. Maori wrasse
  5. Bird wrasse
  6. Hawkfish (flame hawkfish and longnose hawkfish work great)
  7. Orchid dottyback
  8. Neon dottyback
  9. Gobbies
  10. Copperband butterflyfish
  11. Pufferfish
  12. Horseshoe crabs
  13. Goatfish

Some of these fish are not reef safe! If you have a reef tank or even a fowler tank, always do the necessary research to make sure a new fish is a good and safe fit for your particular needs.

The last method I’d like to touch on is a trap. There are numerous versions of diy bristleworm traps out there, or you can pick this one up from amazon.

I haven’t personally used this trap, I prefer to use fish to stave off bristleworms, but I’ve heard great things about it so it might be worth a shot.


Are bristleworms dangerous?

The common bristleworm is a scavenger and will not attack your fish or corals. Their bristles can still be sharp and hurt if you touch one which is why it is always recommended to wear gloves. Fireworms on the other hand are predatory. They can and will try to attack a healthy fish, and even coral, if their size allows. Fireworm bristles also contain toxins that can cause pain similar to a bee sting. As with any toxin it is possible to suffer a more severe reaction that may require medical attention. We always recommend removing fireworms if you see them. Use gloves!



Bristleworms can be beneficial to your tank and aid in the cleanup and maintenance of your tank. It is your personal preference that will determine if you want to remove them or not. Common thought seems to be shifting from removal to the understanding that they are good clean up crew. As always, it is your tank and you should make the final decision in whether or not they stay.

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