The Fish Keeping & Aquarium Guide.

What is a Bristle Worm?

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Many people always wonder how many types of segmented underwater worms we have in the world. There are hundreds if not tens of hundreds of segmented worms in the world. But in this article, let us introduce you to the Bristle Worm. The species of bristle worm come from a Polychaete family of bristle worm.

They are usually segmented, and they like to spend most of their time in darkness. As you might have guessed, they are nocturnal worms. Polychaete means “many hairs.” In Latin, the creature is known by the name “hairy worm” because the first people discovered it believed it resembled a hairy beast.

The bristle worm ranges from small, microscopic worm to the largest, which can exceed 50ft. The worms also vary in color and can grow to lengths of three to eight inches long. Others are either iridescent or luminescent. The bristle worms are cylindrical, and they vary from different worm family to another.

Types of Bristle Worms

There are nearly 10,000 bristle segmented worm species in the world. 98% of the species are marine or brackish, and only 2% or 168 are freshwater species. Bristle worms are nocturnal, and they love staying in the live rocks or the substrate tanks.

They are only visible when you displace the substrate or move the stones and only be seen at night using a flashlight. The worms are in groups of two orders. The sedentary and the errant worms. The errant worm moves with the help of its parapodia.

Sedentary worms do not move so often. They like burrowing or living in tubes. Fireworms are the most notorious when it comes to errant worms, and most people do not like them in their tanks.

Most people do not want them because they usually leave severe pain on the skin if you happen to come across their extended bristles when cleaning the tank. It is recommended never to touch bristle worms with your bare hands as their hairs are thin and easily embedded on your skin, making it itchy.

How to Identify The Good Worms From The Harmful Worms?

Many people believe that more than 10,000 bristle worm species in the world live in our various aquariums. Aquarium owners have gone ahead to classify them into two simple categories: the harmful worms and the good worms. There have been mixed claims about the bristle worm over the years, whereby some people think that they are useful when in the aquarium as they aid in cleaning the aquarium just as the algae do.

But on the other hand, people also think that they are just pests which should not be in our aquariums. When you realize that species of bristle worms have infested your reef tank, you need first to identify which type of worm it is. Some worms are incredibly beneficial to the tanks, but if you leave them alone for a long time, they may end up overrunning your tank, which will end up causing problems to other inhabitants of the fish tank.

Other bristle worms are also carnivorous, so you should make sure that you eliminate them before it is too late. Many saltwater aquarium bristle worms are usually the right types of worms, typically referred to as the Polychaeta worms. They are the detritivore ones and can never cause harm to your fish. All they do is to ensure your tank is clean. They are either pink or grey and are very harmless. You can quickly identify them as they are usually thinner than the fireworms, and even though they are harmless, you are still needed to wear your aquarium gloves every time you are handling them.

Most aquarists advise that you should be careful when dealing with the fireworms. They are harmful worms, but not every one of them is terrible. The bearded fireworms are the most dangerous ones, and they are known as the Hermodice carunculate. The bearded fireworms usually chew the corals, and if you have them in your tank, that will mean a nightmare for your tank dwellers.

The difference between the fireworms and the good worms is their pronounced bristles, which tend to be red at the base, and the worms themselves are gigantic compared to the good warms. The fireworms come from the Amphinomidae family and vary in color from green, yellow, red, or even grey. They can grow to lengths of twelve inches, but typically they are around 6 inches. They can be differentiated from others as they have a short white and red bristles.

How Bristle Worms Find Themselves into the Aquarium?

Most of the bristle worms that we see in our aquariums find their way because we introduce decorations like live rocks and woods that are not clean before inserting them into the aquarium.

It is advisable that you virtually clean the live rocks and wood decorations that you introduce to the aquarium as most worm’s species hide in the wood cracks. The worms are not visible with the bare eyes, so it is easy for us to transport them from one aquarium to another.

How to Stop Bristle Worms from Invading Your Aquarium?

Rocks are essential for most saltwater aquariums. However, not all live rock that we introduce to our aquariums are very safe, This is because most of the hitchhikers like the fireworms, normal bristle worms, or even the Bobbitt segmented worms usually thrive on the live rock that we introduce to the aquarium.

The best solution to preventing harmful bristle worms invading your aquarium is to quarantine the live rock that you will eventually introduce to your tank. The best way to quarantine is by setting up a different tank and bring in the new live stones and some fish food.

Put the fish tank in a dark corner and periodically check the tank and see if you will notice some difference. If the fish food looks different, that only means that something is feasting on the fish food. All you need to do is to figure out what has been snacking of the fish food. Check for a fireworm, bristle worm, or something entirely different. Quarantine the rock or wood decoration is the best way to ensure that you do not bring harmful worms into your aquarium.

Benefits of a Bristle Worm in Your Tank

Both the wild worms and worms in our tanks are so far the best cleaners. They scavenge and eat almost any dead and rotting waste in our tanks. The debris may include leftover foods, carcasses and can also repossess the scraps of creatures killed.

Just as detritus are good at cleaning the tanks in freshwater, bristle worms do the same for saltwater. Bristle worms are the best cleaning crew as they can clean even the tightest of places in between the tanks and clean the crevices. Often will you ever see the bristle worms cleaning the tank as they are nocturnal workers and only clean at night when everyone is asleep? The good thing about the segmented bristle worm is that they tend everything that can decompose in the tank, which will eventually result in a lot of load to the biological filters.

Disadvantages of Keeping Bristle Worms in an Aquarium

Even though most people love the bristle worms species as they help us clean the tanks and keep the aquarium environment clean, they also have a negative effect that they cause to our tanks. It is good to have 1 – 2 bristle worms in your tank as they are enough to do the cleaning, but you are heading for disaster if they exceed five.

Bristle worms love an environment where there is plenty of fish food beneath the tank’s floor or even dead fish carcasses. If you have lots of fish droppings or even leftover fish foods, know that the worms’ population will increase, and instead of a fish tank, you will have a tank full of worm species. Even though the excellent bristle worms species do not inflict a lot of harm, they only inflict a little irritation on your skin. But you can choose to live with them or not.

Simultaneously, fireworms are always eating the tiny fish in the tanks, especially at night when the fish are sleeping. Fish love to sleep in cracks and crevices of the live rocks, so at night while cleaning, the worm tends to eat the tiny, small fish. They can also end up eating the invertebrates like the corals that are inhabitants of the tank.

The last disadvantage that comes with bristle worms is the sting they inflict with their bristles. The pain can be so severe, and, in most instances, you can end up in a hospital emergency room. Fireworms are the most toxic of all the worms, so next time when arranging your tank, you should be watchful of them.

Should We Have Bristle Worms in Our Aquariums?

Anything that does not harm the aquarium is highly advisable to have it as a plus to your aquarium. You will always save money when it comes to the little cleaners. On the other hand, if the worms cause a lot of harm than good, it is good to remove them.

The good worm can be as helpful as the snails or the starfish when it comes to cleaning your aquarium. But when you start noticing the colorful worm species that are exceptionally large inside your fish tank, they might be the fireworms, and it is advisable to remove them immediately.

How to Get Rid of Bristle Worm From Your Aquarium?

Getting rid of bristle worm has never been easy, but there are two ways in which you can eliminate some of the harmful worms in your aquarium. The first one is the old natural predator way, and the second is the bristle worm trap.

1) Natural Predators

When it comes to getting rid of bristle worms in a tank, it cannot be easy, especially when removing them from the live rock. But many natural predators can be used to get rid of bristle worms in your tank. Therefore, they will end up eating all the segmented worms and make sure that your tanks are bristle worm free. They are always the best in controlling the population of bristle worm and other water organisms.

These natural predators include:
• Wrasse
• Arrow crabs
• Bird wrasse
• Maori wrasse
• Sunset wrasse
• Coral banded shrimps
• Dottybacks

While most types of fish, as mentioned above, can blend well with other members of the aquarium, you should make sure that they do not harm other members of the aquarium; otherwise, you will end up having a disaster in your tank. Adding pufferfish or butterflyfish in your aquarium can also help reduce the bristle worm population. They can also add a perfect match to the already existing fish species in your tank.

2) Bristle Traps

If you do not want to add other fish types in your aquarium, using the bristle worms trap is the way to go. You can always buy them at your local aquarium stores, or you can also make them at home using a plastic bottle, a bait, and glue. First, you need to cut 1/3 of the water bottle from the hole of the cap. After cutting it, you need to insert it upside down on the other section of the bottle, ensuring that you glue them together with a non-toxic glue.

It would help if you then placed the trap inside your aquarium, and once bristle worm enters the web, it will be hard for it to get out. The bottle should be at the bottom of the aquarium facing upright, and it needs to be under the sand. This kind of trap is usually the best and most effective when it comes to trapping bristle worms as it uses the get in but no other way out policy.


Whether you consider keeping worms in your aquarium or not, it all comes down to the decision of the owner of the aquarium. It is advisable to have one or two worms in your aquarium as it will help with the cleaning of the tank and maintaining a healthy and clean aquarium. All in all, keeping bristle worms is a genuinely excellent and good idea unless you have an encounter with the fireworms, which are always a disaster.

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