Things You Need to Know About Bristle Worms + Do They Sting?

Bristle worms are segmented worms that belong to the Polychaeta family. Extreme maritime settings do not match their capacity to live, from superheated surrounding waters’ thermal vents to the deepest and darkest chasms in the ocean bottom.

Because bristle worms are nocturnal and live in microscopic tunnels and crevices of rock and wood, they might go unnoticed for years, particularly in metropolitan environments. Bristle worms may be found in various settings, from cold to hot. They might be as little as a speck of dust or as large as 50 feet in length.

Most aquarium species grow between 3 and 8 inches long, while some may reach up to 2 feet. Each segment of the bristle worm’s cylindrical-shaped segmented body has a pair of adhesive leg-like appendages known as parapodia that resemble legs. The parapodia of larger species also serve as respiratory organs and locomotion for the worms.

Ever wondered what an underwater centipede looks like? Well go no further, here we have the Bristle Worm. They are worms that come from the Polychaete family, they are segmented worms and they love to spend their life in the dark. Yes, they are nocturnal creatures.

Bristle worms can be found in salt water aquariums and there are mixed claims about them. Some people claim they are good for the aquarium ecosystem because they tend to eat food that fish leave behind and they clean the aquarium just like an algae-eater, but some people consider them to be pests that need to be eliminated.

In Latin, this creature can be called “hairy worm” because the word Polychaete actually means “many hairs” and by the looks of the creatures there is no objection why the people who first discovered it settled on that name.

Bristle Worm

Bristle Worms Are Precisely What Their Name Implies

We may have seen these worms in our yard or fish tank multiple times, but we have no idea what they are. They are bristle worms, though some authorities classify them as polychaetes.

They are members of the annelid worm family, and they are often found in various water bodies since they are marine species. In addition, they belong to the Animalia kingdom. They have fringes all around them, giving them an earthworm-like look.

Warm-toned hues like red, orange, and yellow make up most of their outer-body design. These segmented worms are bristle worms because the bristly tufts sprout from each segment. They may grow between one and six inches long and up to 24 inches long. Blood is provided to them via three primary blood routes, even though they contain many different components in their bodies:

  • The blood vessels in the central region
  • The dorsal blood vessels are on the backside of their body.
  • The blood vessels positioned laterally (lateral blood vessels)

What actually is a bristle worm and how it affects my aquarium?

Currently there are almost 10.000 species of these worms, some of which live inside our aquariums. They have been classified by aquarists in 2 easy categories: the good worms and the bad worms.

What is interesting about these worms is that their size is hard to be determined. We can have a 8 cm bristle worm that can elongate up to 20 cm or even shrink down to 4 cm! This way they can fit in small holes and can easily move between aquarium decorations making them hard to spot.

Bristle worms find their way into our tanks when we introduce new natural decorations such as rocks and wood that have not been efficiently thermal treated (it is recommended that you boil every natural decoration that you want to introduce in your aquarium, this way you avoid a wider range of parasites, not only bristle worms).

Having one or two of those worms in the aquarium does not pose a problem, they will help by doing the clean-up job. But when their population exceeds more than 5 individuals you know there is something wrong and it needs to be fixed. Bristle worms multiply when they find a good food source, so if you have a lot of dead fish and wasted fish food on the bottom of the tank, then you must know that soon you will have a bristle worm tank instead of a fish tank.

Good or bad worms?

As mentioned above, Bristle worms can settle in one of the two categories: good worms and bad worms. Most of the bristle worms that are found in salt water aquariums are good worms, they help clean up the tank and maintain a good water quality.

When it comes to bad worms, all aquarists fear the Fireworms. But not all Fireworms are bad, some of them are harmless just like the good ones, but there is one species in particular that catches our attention and that is the Breaded Fireworm (Hermodice carunculate). This one loves to chew on corals and it is a nightmare to have it inside the tank.

Fireworms tend to have more pronounced bristles with a reddish color at their base. Their body also tends to be more massive compared to other species of bristle worms.

Stings, doesn’t it?

The bristles, tiny hairy spikes, that these worms come equipped with are their defence mechanism against the outside world. The bristles are quite harmless, they don’t have any toxin or venom on them, the pain comes from the trauma of having dozens of them stuck in your finger.

Many fish tend to avoid them and some that are unlucky will have their scales torn apart by those tiny spikes. That’s why when cleaning up the aquarium or handling Bristle worms it is recommended that we wear protection gloves to avoid being stung.

If the inevitable happens, there are easy methods to get around the pain. Duct tape can be used to remove the spikes from the flesh and vinegar can be poured on the area to relive the pain. Why vinegar? Vinegar is an acidic substance that will counter the effect of the calcium (a base) that coats the bristles.

Getting rid of bristle worms

There are 2 ways to get rid of bristle worms. There is the natural way in which we add natural predators into the aquarium, such as: Pseudochromidae, Gomphosus varius, Cheilinus oxycephalus, Thalassoma lutescens, Stenopus hispidus or Stenorhynchus setrcornis. They will hunt and eat any bristle worm they can find.

Bristle Worm Care and Tank Specification

The other way is by using bristle worm traps. These can be purchased from aquarium stores that sell them or they can be made using some basic materials from around the house. These traps are the same as kitchen bug traps, they let the worm get in and then it can’t get out.

A simple example of a homemade bristle worm trap consists of a taking a water bottle and cutting it 1/3 from the cap hole. After that the part with the cap hole is inserted upside down in the remaining section and it is glued using some non-toxic adhesive. The trap is then inserted into the aquarium and when a worm comes inside it, it cannot get out.

Bristle Worms: What Are Their Functions?

Bristle worms are detritivores that live off uneaten food, trash, and dead animals. It’s debatable whether or not they’re helpful in a saltwater aquarium.

All of that garbage has the potential to disintegrate and emits ammonia is too much for your biological filter to handle. Furthermore, since the ingredients are already on the bristle worm’s menu, they happily fix the situation by consuming the leftovers.

It’s a cleansing technique that wild animals go through, but you won’t notice it as much as you would with your aquarium fish or shrimp.

It’s Unclear What Bristle Worms Consume

Unlike other worms, bristle worms are carnivorous; they feed on plankton, algae, and decomposing organic detritus in an aquarium. They might be gentle and efficient tank cleaners, eliminating trash and leftover food.

Fire worms are a special kind of worm that feeds on corals, crustaceans, and especially anemones in aquariums, posing a threat to the aquarium’s residents.

Take A Look In Your Tank

Don’t be misled by the bristle worm’s frightening appearance, which seems like it came straight out of a Creepy Crawlers Thingmaker. Most bristle worms are entirely harmless, except for their sharp bristles, which may hurt like a bee sting when handled. Because they are scavengers, “good” bristle worms may clean your tank in the same way as snails and certain types of starfish can.

What Are The Benefits Of Bristle Worms?

Even though bristle worms are unattractive and a little upsetting, the vast majority of them are suitable for your aquarium if they are not the harmful kind. By eating organic debris in your tank that would otherwise decompose and generate ammonia, this bacteria reduces the stress placed on your biological filter, which is responsible for processing the waste created.

Bristle worms are primarily scavengers, and if they are housed in a saltwater tank environment, they will consume uneaten food, trash, and carrion, among other things. Some people believe that a bristle worm has eaten a fish body in their aquarium and that the bristle worm is responsible for the death of the fish.

This general rule does not apply to the stinging bristle worms, such as fireworms, which are exceptions to the norm. In some instances, fireworms have been recorded attacking healthy fish (usually undersized) at night when sleeping in a crack or crevice in live rock.

Similarly, as other forms of stings are treated, bristle worm stings are treated similarly.

When Dealing With A Bristle Worm Sting, You Should Follow The Following Measures

You may use tweezers or sticky tape to keep the bristles in place while removing them from the brush. When the rubber cement has cured, you will be able to remove or pull the remaining spines out of their locations inside the skin by eliminating or tugging the rubber cement away from the skin.

  • You should gently cleanse the skin to ensure that none of the spines are damaged or broken off during the washing operation.
  • Using a topical corticosteroid cream or ointment, such as hydrocortisone to ease the symptoms of severe skin irritation or other skin responses, may be beneficial in some instances.
  • If there is any indication of infection, such as pus, redness, or localized warmth, the patient must get medical attention as soon as possible.
  • If you are experiencing pain, using acetaminophen or ibuprofen as advised by the manufacturer may be beneficial in alleviating your discomfort.
  • To relieve the symptoms, skin irritation or other severe skin reactions may benefit from using a topical corticosteroid cream or ointment, such as hydrocortisone. Some patients may benefit from oral steroids such as prednisone.

Is It Conceivable That Bristle Worms Might Harm Humans?

Because of their unpleasant and scary appearance, bristle worms are ubiquitous in our surroundings; it is normal to be terrified of them. Bristle worms are a worm that may be found in the soil. However, the issue now is whether they are dangerous to individuals or not.

Bristle worms are classified as toxic and non-poisonous in terms of harming humans or other invertebrates. As their name implies, Venomous creatures are hazardous to humans and other living things. That’s why you should either handle them correctly or not handle them at all for this reason.

Aside from that, the second snake species, which is non-venomous, poses no threat to humans, albeit they must approach them with great care.

Are Bristle Worms Capable Of Killing Fish?

Brush worms are scavengers; therefore, they will not harm your fish if left alone. Several aquarists have seen bristle worms feasting on dead fish during the daytime. This is obvious because the polychaetes are more likely to approach dead fishes, especially once they begin decaying.

Their bristles carry toxins throughout their bodies, which makes their sting poisonous. Corals, crabs, mollusks, and even other bristle worms suffer due to their presence. When Bristle Worms don’t attack live corals or fishes, they feed on dead corals and fishes since they’re scavengers. If they come across smaller fishes, then there are chances that they may attack and eat the living fish.

The existence of bristle worms in the aquarium is crucial, which is why you should monitor them closely. Any polychaete that isn’t a nematode is classified as a bristle worm. On the other hand, only fireworms may kill fish or make you wish you’d worn thick gloves!

Reproduction In Bristle Worms

Bristle worms must mate as a pair, with the female releasing her eggs and the male releasing his sperm in the same precise spot where the eggs are released.

The rate at which bristle worms reproduce is determined by the quantity of food they ingest. If there is a significant amount of food, fireworms may generate enormous progeny considerably more rapidly than their bristle worm counterparts due to their insatiable eating habits.

The quantity of food you feed your fish, as well as the cleanliness of your reef tank, are both essential to determine how quickly your healthy bristle worms reproduce.

What Do The Bristle Worms Consume Daily?

What should you feed it if you have a chance to keep a helpful bristle worm? The most exciting portion is still to come. Nothing! Therefore, you do not need to provide the worms with specific food for them to live.

Bristle worms are scavengers that prey on decaying organic materials and feces. The residues left behind by other tank occupants and plants are known as detritus in the scientific world, consumed by them.

Bristle worms are scavengers, so they mostly feed on organic matter like algae and decaying bodies of other marine animals, planktons, shrimp, hermit crabs, and dead coral tissue. They don’t attack or kill other living fish and corals.

Bristle worms serve as a kind of full-time maintenance staff for the rest of us, keeping our homes and gardens in good condition. This ominous employee does various tasks, including cleaning, garbage collection, and gardening. Furthermore, they have the extraordinary capacity to maintain cleanliness in your fish tank in addition to aerating the substrate in it.

How To Prevent Bristle Worms From Infecting Your Aquarium?

The bulk of saltwater aquariums needs the use of rocks. However, not all of the live rock we put in our aquariums is entirely safe. Most hitchhikers, like fireworms, normal bristle worms, and even Bobbitt segmented worms, thrive only on the live rock we add to our aquariums.

The most efficient way to prevent dangerous bristle worms from infecting your aquarium is to ultimately isolate the live rock you want to add to your aquarium system. Building a new tank and introducing unique live stones and fish food is the most successful technique of quarantining.

Place the water tank in a dark area of your house and check it regularly to see if anything has changed. If the fish food looks distinct from the rest of the meal, anything feeds primarily on fish food.

To finish your inquiry, you must establish what has been nibbling on the fish food. Look for a fireworm, a bristle worm, or something else different. Quarantine the rock or wood ornament before putting it in the aquarium to avoid harmful worms.


When It Comes To Bristle Worms, Is It Safe To Touch Them?

We should not handle bristle worms directly; instead, we should use gloves to protect our hands. Most worms have bristles that fall off (much like cactus bristles), which allows them to penetrate the skin easily.

What Happens If A Bristle Worm Scratches You?

If you are scratched by one, you may have some localized discomfort. Although wearing protective clothing when removing bristle worms from your fish tank is not required, it is a good idea since certain species of bristle worms are particularly dangerous.

What’s The Easiest Method To Get Your Hands On Some Bristle Worms?

The most common method for bristle worms to enter into your reef tank and establish themselves is purchasing new live rock. All of the beneficial bacteria and other species present in the corals you want to save are preserved, and the bristle worm will eventually show itself when it starts its search for food after just a short time.


Bristle worms are frequent aquarium inhabitants that do not provide a long-term threat to the ecosystem. Several individuals believe them to be excellent tank cleansers in general since they help people live in peace.

Is it worth removing the worms from your aquarium? That depends on how you see the problem. If the bristle worm population is high, it is recommended to do some culling to reduce it. Some worms are beneficial as they clean the aquarium, eat dead fish and leftover food, and maintain good water quality.

Some people do not stand seeing strange aliens like centipedes swarming inside their aquarium, and they tend to be crept by them. But in the end, it is up to the aquarist to decide whether to remove or keep them. We advise keeping small worms as they have an important role in cleaning the water and maintaining a healthy aquarium ecosystem.

But to avoid them in the first place, every natural aquarium decoration needs to be cleaned and sterilized properly, so they are not introduced in the aquarium and feed the fish the right amount of food to avoid having leftover food on the bottom of the tank.

Many people are unaware that they are afflicted since they are tiny, nocturnal, and peaceful. If your bristle worms aren’t harmful, keep them in your aquarium to help create a more natural and balanced marine environment in your home.

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