In the fish-keeping hobby, if you’ve chosen to go the saltwater route and have a marine or reef-style tank, you may discover a crop of little critters that might give you a fright.
They say every hobbyist will experience having them at some point, whether you intended to have them or not. And this is where it gets tricky because there are loads of species out there, and not all of them are good for your tank.
Similar to an earthworm or centipede that looks segmented, these creatures will often show up when you least expect them by hitchhiking on real rocks and other live decors that you may have obtained from your stockist.
But fear not! We will look at the good, the bad, and even the ugly when it comes to these nocturnal worms, which are found all over the world in a huge array of sizes and even colors.
Shall we burrow into more details? Wriggle on for all of the info you’ll need to get a handle on Bristle Worms (Polychaeta’s).
Bristle Worms Overview
A little about their anatomy, which is straightforward enough: they are a typical worm shape, with segmentation along the length of their bodies.
Each segment has pair of ‘parapodia,’ which act like legs on the worm and help it to move around. And then each segment also has a bundle of bristles that look like hair called chaetae. They are sharp and spiky and act as a deterrent to predators. They should also deter you from trying to grab them with bare hands!
With such a huge range of these nocturnal worms out there, what we can also tell you is that there are two categories of these worms.
Errant Bristle Worms use their parapodia to crawl all over your tank and even swim.
Sedentary Bristle Worm species do not get out much and either stay burrowed in the substrate or live in tubes and therefore aren’t exactly movers and shakers. And since they’re nocturnal, you may not even realize you have any. It’s worth doing regular and thorough checks in case they crop up.
98% of the Bristle Worms in the world are of the marine or brackish variety, with the remainder 2% being freshwater. Although their size ranges from huge (50 feet, anyone?) to microscopic, typical species found in the hobby will be a more modest 3 – 8 inches.
When they aren’t hanging out under rocks or crawling around your tank, these worms are scavenging. They act as a great type of cleanup crew that can benefit your tank by removing all dead and rotting materials, uneaten food, and they are great for getting into crevices in the decor of your tank you normally just can’t reach.
It just depends on the type of Bristle Worm that has invaded your tank. Some can be left to do their job if you see fit, while others are deadly and can destroy many members of your tank community.
Frankly, not everyone is happy to look at them either. It’s a matter of personal taste if you leave the good types in or if you’d prefer some happy-go-lucky and personable crustaceans or snails to do the job. Some folks just don’t like the look of them, and your tank is there to be enjoyed.
Spotting The Good Varieties Of Bristle Worms
Well, you may not have asked to have any of these worms in your tank, but it doesn’t mean that you have to get rid of them if you check which type you have first.
And how are you going to see them? Turn lighting off and use a flashlight which will draw the worm out or disrupt the substrate gently, and they should emerge.
If the worms you spot have a colorful body or a dull gray, have bright white bristles or chaetae, and they are evenly spaced along the body, chances are it’s the good kind you can keep if you choose to.
The good types don’t need to be fed; they will find what they want and need in your tank without too much trouble. It will consume fish waste (marvelous!), leftover foods from feeding time, algae, and decaying or dead fish, and other assorted debris.
Spotting the Bad Varieties – The Fireworms
Unknowingly, you may have been the recipient of the variety you do need to eliminate from your tank. These species come from the Pacific and the Caribbean species that will give you endless headaches and possibly a tank empty of other life forms.
They are carnivorous, can damage corals, and can even eat your fish. They have bristles like the good types, but adding to the spiky impact that even the good types can cause, these worms’ bristles are toxic.
This type can also reproduce quickly, so you need to handle the situation fast.
Identifying if you have this type of unwanted worm in your midst is very important, so here are some tips:
- Chances are you’ll easily see them, they aren’t shy and will even eat during the day
- Look out for these worms emerging when you feed your fish; it’s most likely a firework
- They have gill filaments along the body in either red, green, yellow, or brown
- Reddish base for the bristles
- White bristle tips
The bad news is that these worms will actively disrupt your saltwater or reef tank, whether you like it or not.
They are not finicky eaters and will consume invertebrates, crustaceans, and even smaller fish, not to mention compete with your tank community at feeding time for live food sources. They will eat your corals by biting off the exterior and then cleaning out the interior structure.
Types Of Bristle Worms Seen Most Often
Common Bristle Worm
The good kind to have, they are often pinkish and not as plump as some other varieties. They are usually imported in by rocks.
Bearded Fireworm
Short tufts with white bristles and red at the base of each bundle. Bodies are most often red, yellow, green, or grey. Can reach 6 -12 inches long.
Red-Tipped Fireworm
Light-red to brownish body that has a trail of white spots on the body that create two distinctive stripes along the entire length. Heavy bristle bunches are white and red.
Bobbit Worms
Possibly the most terrifying of the bunch, they can grow up to 9 feet long. With a retractable jaw and serrated plates for chewing, they have banded antennae extensions on their heads. Remove immediately or get help from someone who can!
How To Get Rid Of Bristle Worms
These methods will work for both good and bad types, so it’s up to you if you’re letting any of the good ones hang around.
All of these options work, but there are some that are good if you’ve only just spotted your newly landed wrigglers and others that are necessary for a full-blown infestation.
Worm Traps
Considering these worms are mostly an uninvited blight for most hobbyists, there are a plethora of online message boards out there for the hobby folks who will dole out advice.
One of the most popular ways to get rid of the unwanted worms is through using a commercially made worm trap or by making one yourself.
They work like most traps, one-way entry and no way out.
One at-home trap to try is the bottle method. You need a plastic bottle and some quarter-inch diameter tubing that you use to punch into the bottle along its length as the bottle lies on its side. Put these 4-5 inch tube inlets on both sides of the bottle, so you have double the entry points! Use some tiny pinholes in the bottle body so that after you add the paid and close the lid, you can squeeze the bottle to get all of the air out, and it settles at the bottom of your tank.
Add in some sand for ballast, and use dried brine shrimp as bait. Leave for 24 hours with one side of tubing leaning onto your live rocks, and check daily to remove the trapped worms and establish fresh bait. Voilà!
Traps are highly successful for infestations.
Using Natural Predators
Another tried and tested method that is popular is using some of the predators that like to eat these worms. Nature’s way works well for many!
Some of the best things you can add to your tank community that you might like to have included anyway (besides worm management) are:
- Coral Banded Shrimp
- Hawkfishes
- Six Line Wrasse
- Dottyback
- Arrow Crabs
- Maori Wrasse
- Bird Wrasse
- Some Pufferfish species
- Some Butterfly species
This method is useful for infestations, but you need to choose your predator carefully, or it may snack on more than just your worms. And you should be prepared to feed them if they aren’t exclusively interested in eating worms too.
Removal By Hand
While this option is free, it’s not for everyone. The risk of being stung by bristles is inherent and is totally dependent on seeing the little critters in the first place.
You should always wear gloves, be prepared with tweezers to grab them and try to grab them in the middle of their body length so that when they wriggle, you don’t get hit with the spiky bristles. Never pleasant.
Removal by hand is not advised for a large and quickly getting out of control worm population.
Preventing Bristle Worms
Of course, we can avoid all of this if we quarantine any new rocks and decor in the first place. Have a control tank that won’t kill off any of the good things living in your rocks, like bacteria that are beneficial to your tank biome, and remove them when you see them out trying to find food.
Another option is to put any new rocks into a bucket of dechlorinated freshwater which shocks any worms out of their hiding places for swift removal. But beware, this can also remove all of the beneficial organisms. It really depends if you are sure you want a worm-free tank!
If you do end up with an infestation, it’s usually because reproduction rates are high when there is a plentiful food supply around. So it likely means your tank has too much waste, and you need better filtration and cleaning schedules.
Conclusion
Ultimately, to have or have not is up to you, the hobbyist. If the worms creep you out, you have options to do something about them.
If you decide that having a carefully managed worm population works for you as a natural clean-up crew that arrived for free, then they are worth working with.
Much of the information on message boards and forums are all about their good riddance, but having educated yourself on these marine cleaners, we vote for giving the good guys a chance.
