Bristle Worm the Function of the Water Centipede

There are many confronting opinions about Bristle Worm – and their function within the water tank’s ecosystem. Some people say that they are good for the water tank because they help to clean the tank. Some, however, say that they are bad, especially since they can hurt your fingers. But it happens when you clean the tank without thick gloves. So, what is the function of this worm – and how can they affect the water tank’s ecosystem?

bristle worm

More about Bristle Worm

If you want to know the physique of an underwater centipede, then that’s how a Bristle Worm looks like. They originate from Polychaete family. They really love being in the dark – as they are nocturnal creatures. They are included within the category of segmented worms. Some people may call them the ‘hedgehog’ worm – and there is a good reason for it.

You can find this worm in salt water tank. Some people say that this worm is helpful because they share similar trait as algae-eater. They eat food (that fish would leave behind) and they clean the aquarium. However, some people consider them to be pests – and these pests must be eliminated.

The word Polychaete comes from Latin word which means ‘many hairs’. That’s why this worm is also called the Hairy Worm because it seems that they have so many hairs sticking out from them. The worm current has 10,000 species – some of them live inside the water tank. Aquarists classify them in 2 major categories: the good worm and the bad one.

You can’t really determine the size of the worm. It’s possible that an 8 centimeters worm can elongate to 20 centimeters or even shrink to 4 centimeters. Because of their flexibility, they can move between the decorations (usually found inside the aquarium) – making them difficult to spot and also to catch. They can also fit in small holes quite easily and conveniently.

How does the Bristle Worm come to the water tank?

Well, when you bring in new (and natural) decorations, like wood or rocks that haven’t been thermal treated efficiently, it’s possible that the worm will find their way into the tank. That’s why it is recommended and advisable that each natural decoration (that you want to include in the water tank) to be boiled first. This method won’t only avoid Bristle worm but also a various types of parasites.

The worm isn’t appealing or interesting at all. To be honest, they are ugly. Some even say that they are disgusting. With millipede-look-alike appearance, who wouldn’t be disgusted by the creature? This cryptic, small, and segmented worm lives in a reef aquarium – under the rock or in the sand. They mainly consume decaying stuff and detritus. The hair is the trait that makes this worm unique. If you can find a detailed picture of the worm, you will see bristles coming out from both of their sides – left and right. These hairs have their own functions – as protection from predators.

The Food of Bristle Worm

What do they eat, anyway? Well, they are detritivores. They would dig through the tank’s detritus, gunk, and muck. When they find rotting stuff, it’s likely that they will eat it. The rotting stuff is the main reason why the water quality has been spoiled. By eating those stuff, the worm indirectly helps maintain the cleanliness of the water tank. These worms love eating biological and food waste – even rotting carcass of the fish. Be aware of these wastes and carcass because they add nitrates, nitrites, and ammonia to the water. As a result, it will be responsible for spoiling the water parameter that you try to maintain extra hard.

What Does the Worm Do?

These hedgehog-like creatures are doing the nasty job that no one else does. They clean the aquarium by consuming decaying biomass and dead bodies from the tank. Can they kill fish? Or will they kill it? Well, it’s unlikely. Bristle Worm is basically scavengers. It means that they would eat dead stuff and leftover food inside the water tank. If you catch them eating a dying coral or a dead fish, big chances that the fish (or the coral) die first. And then the worm is attracted by the decay smell.

Is this worm a type of parasite?

Not at all! You see, parasites would live in (or on) the host and then feed the host off. This worm, on the other hand, eats off decaying and dead matters. So, they are two completely different creatures – and Bristle Worm isn’t a parasite, for sure. This worm isn’t considered dangerous for humans either. However, it is always advisable to wear thick gloves whenever you put your hands into the water tank. You don’t want to take chances. The worm stings – and it hurts quite bad. That’s the ‘harmful’ effect of this worm to humans. The sensation is quite painful, sharp, and direct. And as if it weren’t enough, you may be left with splinters – and you need to figure out a way to remove those splinters. Remember, they are pretty tiny so you may take quite a long time to remove them all.

Basically, the worm isn’t dangerous. It can even help you manage your aquarium’s ecosystem and maintain the cleanliness. But you need to remember that the ‘hairs’ are pretty dangerous – at least they can inflict pain quite so bad. So, always remember to wear thick gloves whenever you have to clean the aquarium or put your hands into the water.

Getting Rid of the Worm

So, if you are thinking about getting rid of the worm, what should you do?

  • You can remove them physically whenever you see them
  • You can add the predator that will eat them and make them the food source
  • You can use a Bristle Worm You can either make it your own or buy it
  1. Removing Them

You can use simple tool to remove them. Although some people may use their hands (covered in thick gloves, of course), it isn’t advisable. It’s better to use a scooping or grabbing tool. Whenever you see them, just grab them. You can even use a turkey baster or a gravel vacuum to suck them.

  1. Making Bristle Worm Traps

There are some DIY methods that you can try. The first one is the soda bottle conversion. You can cut the top part of a bottle with a knife or scissors. Be careful as the edges are sharp. Remove the cap and then invert the top part into the remaining part of the bottle. Don’t forget to superglue the sides so the bottle would be completely sealed. Place a rotting and smelly bait right inside the trap. Just lay it down sideways. Locate it on the bottom side of the tank. And just leave it. It would be a good idea to change the trap once in two or three days.

Another option is to use DIY food (storage) container trap. Instead of a bottle, you use a rectangular container with its lid. Make sure to go with the flattest container. Simply cut the top part of the lid in X pattern. As a result you create 4 plastic and sharp triangles that can flex right in the middle. Push each part down – and bend them. You should now create a (semi-permanent) gap that is big enough to capture those worms. Be careful when pushing and bending as each of them would be sharp. Leave a bait with something gross and smelly stuff inside the container so the worm would be lured into it. Place the container on the bottom side of the water tank. Check every day or once in two days.

  1. Using Predators

So, what are the suitable predators to deal with this worm? First option is the Arrow Crabs. Its main ‘menu’ is the worm. Another hunter is the Coral Banded Shrimp. They mainly prey on the worm. Despite all of the unattractive hairs and physical appearance, these predators LOVE the worm so much.

Coral Banded Shrimp


There are also some fish (the saltwater type) that favors this worm so much. Melanurus and Wrasses are pretty effective predators. Dottybacks are also useful. Hawkfish love eating small invertebrates – and it is possible that the worm would be included in their menu.


You need to know that choosing natural biological control, like adding the predators, does take some time. You can’t expect a fast and total elimination of the issue. Not to mention that individual result will vary. So, if you expect fast result, then this method may not be the best option for you.

Should You Remove the Worm – or Not?

In the previous sections, we talk about methods to remove them. But does it mean that you should get rid of them? It’s basically up to you, but you should also check the situation of your aquarium. You see, Bristle Worm is a biological (and natural buffer) that helps to clean the aquarium’s ecosystem. It’s like the cleanup crew that happens incidentally – you didn’t intend to have one. As it was mentioned before, the worm has its own function and use – and it’s Mother Nature that you need to thank to.

All you need to do is to monitoring their population. If they are under control, just leave them be. But if the worm starts to develop into a problematic case and they grow into a bigger population, then you can consider about removing them. Or if you are truly disgusted and annoyed by their existence – and you can’t stand them – then removing them would be your only option. But other than that, leave the Bristle Worm alone and you can co-live together in peace.

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