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Live rock comes with a lot of perks, but sometimes it also comes with uninvited hitchhikers. One of the more problematic of these critters are bristle worms, a genus of creatures that can make short work of your invertebrates and corals. Once they’re in, you’ll need to get them out!
Let’s dive right in and I’ll teach you how to remove bristle worms from your tank and keep them from becoming a problem again.
What You Need to Remove Bristle Worms From Your Tank
You don’t need much to get rid of these worms, but it’s going to take persistence and care.
Bristle worms are all members of the family Polychaete. They’re generally small, under the 4” range, and are common across the ocean in different biomes ranging from coastal reefs to underwater methane vents.
The ones that get into your aquarium are the coastal kind, and they have a tendency to be coral eaters. They can also have a nasty sting, which makes removing them a problem. Like many pests, you’ll have to do more than just grab them out of the tank whenever you see them.
Removal is a three-part process, we’ll do the following:
- Physically remove worms as often as possible.
- Create worm traps to catch them even when we’re not present.
- Find a long-term solution by using something that predates on bristle worms.
We’re going to need a few things to make this happen:
- Turkey Baster- The ideal solution for taking care of small-to-medium-sized worms is a turkey baster that you’ll be using like a giant lab pipette.
- Net- Nets are another good method for removal when they can be used.
- Long Tweezers- To get down into the rocks and grab the worms safely when other methods won’t do.
- A Tupperware Dish or an Empty Soda Bottle- For making a worm trap, cheaper Tupperware with lighter lids will be easier to work with. You’ll need aquarium silicone if you opt for a bottle as well.
- Scissors or X-acto Knife- To make your trap.
That will get you through the first two steps. For the last step you should also make sure that you have room for whatever predator you choose to handle the problem.
Do I Need to Remove Bristle Worms?
For the most part, you really don’t want them in your tank. They eat corals and invertebrates and they can cause a painful sting if you come into contact with one.
Any member of the family can cause problems, but in a system where they’re not capable of eating your fauna they’re not particularly harmful. I’d still remove them just to avoid problems in the future.
Bristle worms are primarily detritus scavengers. In a tank where they’re harmless to the fauna, they’re not necessarily a bad thing. You may still want to remove them to avoid coming into contact with them.
That said, it’s hard for an amateur to correctly distinguish the species and you’ll need to catch one to identify them in the first place.
For anyone who doesn’t have in-depth knowledge of bristle worm taxonomy, it’s generally just easier to remove them whenever they’re seen. Removing them will do little to no harm, leaving them in can cause major problems.
Are Bristle Worms Dangerous to Humans?
Most worms have spines that will stick in you if you handle them. These spines are similar to the thinner needles that often surround the primary needle in cacti. If you’ve ever brushed a barrel cactus then you have a good idea of what it will do to your hand.
On the other hand, some species carry more noxious venom that can cause you to become ill. They’ll also bite if you grab one, which is painful on its own.
If you come into contact with a worm then you should apply basic first aid:
- Remove the bristles with a pair of tweezers
- Apply hydrocortisone cream 3 times daily
- Watch for signs of infection
- Contact a doctor if symptoms don’t improve, if they include nausea and vomiting, or if signs of infection (redness and swelling, pus discharge, or blood poisoning) begin to show up.
You’ll be fine after most incidental contact. The fact that you took a puncture wound in an environment designed to harbor bacteria is a larger factor in most cases, but occasionally a true “fireworm” ends up as a hitchhiker and the venom can be pretty nasty.
In all cases, your first step should be to remove the spines and disinfect the area. With more painful species your hands may be a bit shaky when you go to remove the spines even if you didn’t receive a dose of venom. It hurts.
In all cases look for signs of allergic reactions. An allergic reaction can be a serious medical matter if it’s severe. Signs include trouble breathing, excessive redness, and hyperventilation after being stung.
In that case, you can use Scotch tape or packing tape to remove the hairs. Just pull the tape over the affected area, tight to the skin, and then remove it. You’ll lose some hair on your hands but it should remove all of the bristles on your skin.
I’ve been unable to find reports of anyone dying after bristle worm contact, but there’s a large gap between “not lethal” and “safe” that should be accounted for. Their venom and its actions are well understood since both divers and saltwater aquarists come into frequent contact with these pests.
1. Begin With Physical Removal
If you’ve noticed worms in your tank, then you should take action as soon as possible.
Most of the time, these worms get noticed when they’re still fairly small. Anything under ½” can easily be picked up with a turkey baster or large pipette. Just squeeze the bulb, get the tip near the worm, and let it go. The worm will come in right alongside the water.
Larger worms should be grabbed individually with tweezers and disposed of whenever they’re seen.
Most of these worms are tiny when they’re first noticed. Lengths of 5-10mm (.2-.4 inches) are common. This can make them hard to distinguish, and you want to do so before they become a problem in your tank.
You can also try isolating pieces of live rock in a bucket. Add a small powerhead to produce some current and the worms will come out to feed and float at the top of the bucket. A net will allow for easy removal at that point.
If you have a refugium and have filter socks equipped in it you can also move the rock into that location and remove the worms from there. Macroalgae may make it a little bit more complicated but its doable and keeps the live rock in the system.
Physically removing worms can cut down an infestation but may not be enough to remove all of the worms. This is just our first step at immediate damage control.
If you see very large specimens in the tank, chances are that there are many, many more small ones lurking in the rock. These worms reproduce asexually via budding, so just one mature specimen can create many more in the tank.
Systematically working through your bits of live rock may be possible in some tanks, but that’s not always the case. I still recommend keeping tools near the tank and grabbing any worm you see while you’re observing the aquarium even if you were able to get rid of most of the critters this way.
Some will comb the substrate as well. If you choose to go down this route you’ll need gloves and a lot of time. Just remove a few handfuls of the substrate at a time, put them in a casserole dish, and go through them carefully with tweezers. This will help thin their numbers but it’s not realistic to try removing all of the worms in this manner.
2. Create a Worm Trap
Worm traps are commercially available and relatively cheap. It’s still faster and cheaper to rig a trap at home in most cases, and they’re not any less effective at capturing worms.
I prefer to use a Tupperware trap. It’s a pretty simple process:
- Remove the lid of the Tupperware. Use the flattest, smallest one you have on hand.
- Cut an X into the top of the Tupperware, making four triangle-shaped flaps.
- Press on the plastic repeatedly until it stays bent with a very small hole for the worms to enter.
- Bait the trap with food of some sort.
Bristle worms aren’t the smartest of creatures. They’ll go through the hole seeking food, but have a much harder time finding their way out. Of course, they’ll eventually get out of there but 90% of the time they’ll just sit in the tupperware munching on the bait.
You can do something similar with an empty soda bottle:
- Cut the top of the bottle off, just below where it stops sloping outwards.
- Invert the top and stick it into the bottle, the opening should now be properly inside the bottle.
- Affix the pieces together with a touch of aquarium silicone.
- Bait the trap and place it in your tank.
This one operates on the same principle and is also simple.
People do make more involved traps, usually out of PVC. In the case of a serious infection, this is an option. That said, it will cost as much as a commercial trap while being only marginally more effective than the traps above.
Dispose of the bristle worms after capturing them and continue to monitor the tank.
I recommend using the trap each day until you no longer find any worms in it for two or three days running.
This means the bulk of the worms has been removed, but it doesn’t prevent recurrence if there are still offspring lurking in the crevices of your live rock.
3. Use Predators for Long Term Control
There are two complications to long-term control. The first is that these worms breed prolifically and don’t need a mate to produce more of themselves. The other is that they tend to get into places where it’s impossible to chase them like in the substrate.
Fortunately, you don’t have to chase them down. Instead, we find some fish or invertebrates that can handle the problem for us. What you pick is determined by your taste and the inhabitants already in the tank.
A favorite for most aquarium keepers is the various species of Wrasse. Most of them will eat bristle worms to some degree, but do your research on the individual species. Some, such as Fairy Wrasse, won’t go after them at all.
A Six-line Wrasse comes highly recommended for this task. They’re voracious little micro predators and they’ll thin bristle worm populations with no difficulty.
Other good choices include Dottybacks and Hawkfish. Just double-check and make sure the species you’re considering is one that will actually eat the bristle worms. Some Gobies, Puffers, and Goatfish are also up for the task.
Invertebrates are more convenient to use as predatory bristle worm control in most tanks. In that case the following creatures are good picks:
- Arrow Crabs
- Coral Banded Shrimp
- Olive Snails
All three of the above are known for eating bristle worms but you may be able to find other options.
While predator control is a good thing, it’s not always the best option. Most creatures that will eat bristle worms can also eat other inhabitants of the tank, and some of the fish that are best for their control can have aggression problems.
The key to long-term success is remembering that most of these predators primarily eat baby bristle worms. You’ll still have to figure out something to do about any of them that have serious size through either physical removal or trapping.
Get Rid of Your Bristle Worms Today
Bristle worms are a constant problem for those who keep saltwater aquaria, but they’re manageable as long as you use the right strategy. This starts with physical removal and includes a long term solution to the problem in the form of predatory population control. It’s an easy task for most aquarists, it’s just a matter of knowing what to do when the time comes.
And the best time is today, why not get started on controlling your bristle worm problem right now?