Terrible Advice Tuesdays (T.A.Tues): Death Looks Like Bristle Worms


Terrible Advice Tuesdays: Bristle worms kills corals, are overall bad things and should be removed from your tank.

The rest of the story: Poor bristle worms. Most people seem to have it out for them for really no good reason!

Nearly all Bristle worms are valuable members of clean up crews as they are great scavengers. Of course there is always the story of a bristle worm eating a fish/coral/clam/you-fill-in-the-blank and nearly all the time the fish/coral/clam/you-fill-in-the-blank died, or was dying, and the worm came and cleaned it up. I’ve also run across stories of bristle worms growing to feet and length and while pictures can provide evidence, most bristle worms get to be 2-6″ (5-15 cm)

Yes, bristle worms can sting. Their bodies are covered in hair looking projectiles that dig into your skin and burn. Personally I’ve been able to avoid getting stung by simply watching where I’m putting my hands in my tank. Wearing gloves never hurt either.

I’m a fan of bristle worms and I’ll often bomb a tank with them to establish a population of these worms. If you don’t like them, or think you have too many, you can remove the worms with a pair of tweezers. Arrow crabs also do a good job of eating them.

Bottom line: leave the the bristle worms alone!

Browse the Store! Questions?

Comments for this article (22)

  • Darren says:

    I’m so glad you did a piece on bristlies. I’ve been fighting their corner since I got into the hobby. So many people are desperate to remove them due to the horror stories. I feel so sad when I see someone shouts “FIREWORM KILL IT!”. Thank you, Mark.

  • dave says:

    I THINK they didn’t get the memo in my system. arrow crabs are afraid of some in my system hell I am too.

  • Steven says:

    Hi, I have witnessed a larger worm rear its head, flatted its body and fan it’s head out like a cobra and attack a young mandrin and kill and eat it. No u can argue it was sick but I belive it was just the right size.

  • Matt says:

    I make space for Bristle Worms in my tank… the bottom of the weir is rife with them and amongst the pods and other fun things they’re safe and sound doing a great job…

    Steven… sounds more like a Eunice Worm to me?!? A bristle worm would have to be a MONSTER to take down a healthy fish and as Mark points out, live happy things aren’t their choice meal…

  • Steven says:

    It seems true if they reproduce fast enough that their food source is low that they would turn to other sources. Also the way of the ocean is the bigger it gets, the bigger it’s food gets.

  • Steven…bristle worms move slowly and don’t move in the way you described. What you witnessed was likely either a bobbit or eunice worm. Those worms are trouble and should be removed from your system

  • Weatherman says:

    I have had personal experience with bristle worm trouble. I converted my Nanocube 24 to be a pearly jawfish habitat. I got a pair, put them in and they began to establish their burrows. A few days later one of them turned up dead with huge blister-like sores on its body. Shortly there after, the other one suffered the same fate. I could not figure out what was causing this. My water parameters were fine and I didn’t have any stinging corals in that tank and no other fish, just hermits and snails. I sent a couple of pictures into wetwebmedia and Mr. Bob Fenner wrote me back asking if I had any stinging coral or bristle worms in my tank. I told him I did not have corals but did have bristle worms. He said he has seen that before. The problem is that since jawfish are burrowing animals and bristle worms live in and on the sand primarily, they come into contact with each other. And apparently, jawfish do not handle bristle worm stings very well. So, just a heads up to any one planning on keeping burrowing or bottom-dwelling fish, especially if they are gentle, peaceful fish like pearlies. That being said, in my 90 gal reef tank, I find the bristles to be a valuable part of my cleanup crew. I just wish I could train them to eat mushrooms!

  • shaun, UK says:

    I think we need to spread awareness of the difference between a brittle worm and fireworm so people know when they see a worm they know to leave it or kill it.

  • GainesvilleReef says:

    Weatherman,
    That sounds like vibrio infections. I lost some anthia’s that way. They were eating off of something dead or rotten in the tank. The sores look like something took a chunk out of them.

  • Beetle says:

    Hey I agree Mark,Ive always had bristle worms and I have never seen any damage from them, I did pick one up once to show a friend (I didnt know about the bristles at the time) and ended up with heaps of little white projectiles stuck in my thumb and forefinger , fortunatly there were no serious effects, just some severe itching,but I would NOT recommend any one pick them up with your fingers.
    Bruce (beetle) Bailey

  • Elmo says:

    Very timely with this advice. I was just about to post this question to some of the forums because of conflicting information I had been hearing. When I got started a year ago, it seems the common advice was to eliminate all bristle worms. Then I started hearing bristle worms are okay, but not fireworms. Lately I have been hearing that most types of bristle worms are a sign of a healthy tank. Amazing how fast things can change.

  • Lee says:

    Well, I used to say they are harmless due to all the data out there that suggested so… however I saw a group of them take down a healthy fish in my tank. The main aggressor was this guy here: http://youtu.be/evbNIxH1weE?list=UU-JgIzlMQrm6sv5GvNLbWpA

    I also found several scientific articles regarding the bristleworm family and how they can all turn redatory when food is scarce. Here is an article compiled by other hobbyists: http://www.reefs.org/library/article/r_toonen12.html

    I have studied (leasure not scholastic) enough wildlife to know that even the most devout scavenger WILL attack and kill even healthy animals when food is scarce and the opportunity exists.

  • I had a large amount of Bristle worms in my tank, was going to leave them be but when my lights went out it looked like my rocks were moving there were so many! Had a very large one that came out at feeding time that I finally removed with tweezers, and ended up just getting an Arrow crab to control the population. now there are a few here and there, but doesn’t look so creepy 🙂

  • Lee…your worm looks like a Eunice, which is a predator.

  • Matt says:

    I have to agree with Mark… that’s almost certainly a Eunice… bottle trap it and mind your fingers!

  • Sara says:

    It is funny how many people get the notion that bristleworms are bad to have in your tank. The only reason why I hate them is because it hurts when you accidentally touch them. My fingers will swell and I’ll get blisters wherever one touched me. But they are bad in seahorse tanks. Seahorses sometimes think the can eat them and get bristles stuck in their mouths. I’ve also seen a neon goby covered in bristles once, but it survived. I think it backed up into a hole a bristle worm was in.

  • Pierre Bouic says:

    An older tank buddy of mine some years ago got so live rock from the Great Barrier Reef here in OZ from a supplier who gave the option of rock untouched in any way (other than picking the visible crabs off) and after it was set-up he’d been raving about the life in his tank without having any fish yet (still cycling it) when I saw it under actinic light bristle worms of all colours were everywhere, I mean really beautiful one’s. So he said he was going to make an area especially for them to feel at home at one end of his tank away from all corals. Months passed and when I came back to check his progress the bristle worms were out during the day with fish not worried about them and lots of soft corals had worms on their bases. He didn’t have any losses from worms of any kind & the rock had pop-up corals both hard and soft all over. I thought to myself how’s he getting away with this, cause it went against all I’d ever been told for rocks and pests. Well this guy was picking crabs out for months but still wasn’t losing fish or coral. I didn’t know bristle worms could be so varied and comfortable out in the open, most were really fuzzy like pipe cleaners that were multi coloured, you’d have thought he’d made a show tank for displaying bristle worm species. When he moved house during break down he found 2 crabs in the weir as big as his hand. Anyway I agree with Mark on this one, as I’ve got plenty of BW’s and not had problems, as for pistol shrimps that’s another matter, darn things #@%& hate em.

  • Lee says:

    Its not a eunice. Eunice are round, this one is flat.

  • Will says:

    Can bristleworms be a good addition to cleanup crew? Yes, most species, but I for one, don’t want them. Only the vast majority are reef safe. I don’t pretend like I know all the species, and I like my clams to stay alive. They’re too similar to other pests for identification, and I believe most creatures are opportunistic. If/when the food runs out, who’s next? Probably my defenseless creatures. When I see them, I try to remove them.

  • Al Ulrich says:

    Joining the conversation very late to the party, but completely agree. I also hear from people who are concerned about bristle worms. They are a great, natural clean up crew and get blamed for problems they didn’t create.

  • They get alot bigger than 2-6″ Mark, 5 years ago I pulled two out of my 300g tank that were over 3 feet long, so the 2-6″ remark in the story above is highly inaccurate and misleading. So if you, being in the position of where people in the hobby trust your videos and information as being correct and positive, you need to provide accurate information and not mislead people. Now people are going to think that bristleworms never get over 6″. I am going back into the Saltwater club I am a member and discredit your article above as highly inaccurate that another member posted. This is what I am talking about, about your position.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.