Bristleworm?

Dear Yvonne:

No doubt that was an errant bristleworm you spotted (for hobbyists purposes, these polychaetes can be characterized as either sedentary or sessile species — i.e., harmless tube builders and filter feeders that stay in one place — or errant species that wander about in the aquarium and scavenge or hunt). In my experience, there are three circumstances during which the errant bristleworms become problematic in the aquarium — when they become too large, when they become too numerous, and when they are the notorious fireworms rather than the ordinary, run-of-the-mill, garden-variety bristleworms. Errant bristleworms have powerful jaws and specimens larger than two or three inches in length can deliver a painful bite. (Some species even have poisonous bites, although they’re not normally dangerous to humans; the bite is only about as bad as a bee sting.)

Virtually all of the errant bristleworms are literally bristling with urticating spicules that penetrate the skin and break off on contact, giving these prickly pests their common name. The embedded spicules are always irritating and the wounds they cause tend to become easily infected, and in the case of the rare but dreaded fireworms, the poisonous spicules are extremely painful. For this reason, it’s a good idea to wear protective gloves when working in an aquarium that’s known to house bristleworms, especially when you are rearranging the live rock.

Here is an excerpt from Mike Noreen’s Bristleworm FactSheet that explains a little more about how the wandering or errant bristleworms can sometimes cause trouble in the aquarium:

<open quote>
3. Errant bristleworms.
The real problem childs in tanks. They are ugly, move in an unnerving
manner, can pack nasty poisonous bites and/or poisonous bristles, and may
eat things the aquarist would not like them to eat. In general appearance
they resemble centipedes (although the ‘legs’ are not true legs, and they
are not related to centipedes), and are always present in all tanks with
live rock or live sand. They are of varying colour, size and disposition,
and a great number of families and even greater number of species are found
in aquaria. It is very common for errant polychaetes to be opportunists –
eating algae, scavenging, or killing small evertebrates as they find them.
Despite their omnivorous habits the vast majority of species are totally
harmless in a reef tank. A very few species may, however, cause problems.

4. The Bad Boys.
Errant bristleworms cause problems in two ways: either by becoming so big
that they can attack things they normally would not be able to harm (ie
fish or aquarists fingers), or by being predators/parasites on valuable
inhabitants in the aquarium.

Bad because of size: Basically a bristleworm larger than, say,
two-three inches can deliver painful bites, and conceivably kill fish,
shrimp etc. Some species also have poisonous bites, and although I’ve
never heard of anyone dying of bristleworm-bite, there’s no doubt they
could seriously inconvenience a sensitive person (normally a bite from
a poisonous species, ie a Glycera, is comparable to the sting of a
wasp). Use caution (and/or tweezers) when dealing with a large worm.

Bad because it’s a specialized predator/parasite: Actually very few
bristleworms are parasites, and none on vertebrates, so the fish are
safe (except for very large very hungry predatory worms). Some species
do eat corals, and may cause problems. The most known coral-eating
species is the Fireworm.

5. The Fireworm (additions welcomed):
The Fireworms are a group of coral-eating worms from the Caribbean, common
in shallow waters. In general appearance a fireworm is fat, fatter than an
earthworm, reddish-brown, with prominent tufts of white-to-green bristles.
They can multiply rapidly, and can in a short time kill all corals in a
tank. They have gotten their names from having poisoned bristles, which
cause skin irritation. Handle with care. Various methods have been
suggested to remove Fireworms. These include: commercially sold traps,
mechanical removal with tweezers, putting something tasty (ie shrimp meat)
in old nylon stockings in the tank overnight. The worms become entangled in
the nylon, and can be removed in the morning. If I sound somewhat vague on
fireworms, that’s because I’ve never even seen an actual fireworm.
<Close quote>

In all probability, the bristleworm you spotted is completely harmless, Yvonne, but when you see one there are almost certainly many more, so it would be appropriate to take steps to thin out the bristleworm population at this time in order to prevent them from becoming too numerous or growing too large. Here is what I normally advise hobbyists in that regard:

Bristleworms In the Seahorse Tank

In general, bristleworms are benign, even beneficial inhabitants of a seahorse tank that perform a useful service as scavengers. But when their numbers get out of control or they grow too large, there comes a point when an overabundance of bristleworms becomes problematic as far as seahorses are concerned. That point is generally when the exploding population of bristleworms become too large and aggressive at feeding time, actively seeking out the frozen Mysis even during daylight hours, no longer content with cleaning up leftovers, and begin invading the feeding station. Too many bristleworms lingering too long at the feeding station brings them in direct contact with the hungry seahorses who come to the lunch counter for their favorite food as usual. The galloping gourmets may accidentally brush up against the encroaching bristleworms, or even attempt to perch on them, and they may get a snootful of bristles when snicking at the same mysid a bristleworm has taken an interest in. Even if the seahorses don’t inadvertently snick at them, the bristleworms may shed a few of their irritating spicules while they are at the feeding station, and the hungry seahorses can then accidentally ingest such loose spicules when slurping up frozen Mysis. Captive bred seahorses are aggressive eaters that are accustomed to slurping up food from the bottom, and it seems at times this may also lead them to strike at baby bristleworms. I’ve also heard a few reports of seahorses that snicked up a tiny bristleworm and got them lodged in their snout or throat. It’s unclear in these cases whether the bristleworm was accidentally sucked up while the seahorse was targeting a piece of nearby Mysis or whether the seahorse actually mistook the tiny worm for something edible and deliberately struck at it, but this is another potential danger the seahorse keeper should be aware of.

I have seen pictures of seahorses with bristleworm spicules embedded in their tails and snouts as a result of such close encounters. These injuries are usually minor, easily treated by removing the spicules and administering antibiotics orally via gut-loaded shrimp to prevent secondary infections, but the more bristleworms there are, the more likely such incidents and problems are to occur.

I have seen a few seahorse tanks that were overrun by them to the extent that the bulk of the total biomass in the aquarium consisted of bristleworms! When that happens, they are detrimental simply because of their effect on the water quality. Under certain circumstances, the total metabolic activity of the countless bristleworms may have a greater impact on the nitrogen cycle that all of the seahorses and their tankmates.

So when you start to see bristleworms swarming the food station, it is a good idea to start thinning them out. You might consider using a form of biological control to reduce the bristleworm population. For instance, Arrow crabs (Stenorhynchus seticornis) are predatory on bristleworms. Large arrow crabs can sometimes be problematic for seahorses, but in my experience they get along well together. You might want to try a medium-sized Arrow Crab, which will predate small bristleworms and help keep their numbers in check.

Although arrow crabs will happily devour any bristleworms they can catch, they won’t eradicate them entirely from your aquarium. Too many of the bristleworms always remain inaccessible to them within the rockwork and sand for that, but a small to medium-sized arrow crab or two can help control the bristleworm population. A fairly effective way to reduce their numbers is to regularly trap large bristleworms after lights out along with keeping a young arrow crab to thin out smaller worms (providing there are no sessile invertebrates in the tank the crabs could harm).

In my experience, small to medium-sized arrow crabs are safe with large seahorses and can be used to help limit the number of bristleworms in your tank. But if you want to try this, you don’t want to pick out the biggest, baddest, bruiser of an arrow crab to do the job! Go with a smaller specimen, keep a close eye on it, and be prepared to replace it with a smaller individual after it molts once or twice. They grow fast and can nearly double in size after each molt.

Remember there are always exceptions to every rule, and large crustaceans are never completely trustworthy. Even the most harmless and seemingly inoffensive crabs can cause trouble under certain circumstances. For example, not long ago I heard from a hobbyist that had been keeping a decorator crab in his seahorse tank. All went well at first and there were no problems of any kind for months until, for no apparent reason, the crab suddenly began to quite deliberately amputate portions of the seahorses’ tails. It was not attacking the seahorses as prey or attempting to eat its mutilated victims, it was merely methodically harvesting portions of their anatomy with which to adorn itself! It was simply doing what all decorator crabs do — snipping off and gathering bits and pieces of its immediate environment to attach to itself as a form of natural camouflage. It just goes to show, with crabs you can never be sure how things are going to work out…

I would characterize arrow crabs (Stenorhynchus seticornis) as opportunistic omnivores. I have kept them in a number of my aquaria over the years, including a few seahorse tanks, without any problems. They never bothered my Hippocampus erectus at all, but they can be hard on sessile invertebrates in general and I certainly wouldn’t trust them with dwarf seahorses. Nor would I trust them with a small bottom-dwelling fishes like gobies.

And of course you can also control bristleworms by trapping them. A number of bristleworms traps are available at aquarium outlets and can serve as the seahorse keeper’s first line of defense against these prickly pests. Here are some tips from Dee that explain the best ways she’s found for trapping bristleworms:

deemarie1234 <[email protected] <mailto:[email protected]>> wrote:
Hi,

I actually caught a bristle worm last night that’s massive!!! Only 4"
long but nearly 1/2" wide! I used a trap for him. I wasn’t going for
him. I knew there was a big one in my reef tank and had seen one
about 7" long. He was the one I was after. My hubby woke me up this
morning to come see the one I did manage to catch.

Besides him though I’ve caught quite a few smaller ones as well. I
like to check my reef tank about 1 1/2 hrs after the lights have been
shut off. Then when I find them I watch them as they flee from the
flahslight and know where they are hiding. I set the traps right next
to their hidy holes and catch them. If they are really narrow the
traps aren’t that good. They can get back out very easily so you
can’t wait until morning to check the traps. You need to check them
periodically through the night, if a small worm is in the trap, empty
it then don’t wait till morning or he’ll be gone. Even the huge one I
just caught managed to get into a hole about 1/8" in diameter to the
food chamber.

I’ve had better success with nylons. I buy knee high nylons and at
night drop a rock or two in the toe along with some food. Then I set
the toe area right near the holes. When they try to get the food they
get stuck in the nylons. In the morning I just pull it out of the
tank and get rid of them.

I’ve also used a turkey baster a few times. If you can get into the
tank quiet enough they won’t really move, squeeze the ball and when
you’re really close to the worm let go. The suction can be pretty
good sometimes depending on where they are.

Dee

> Anyone out there with any great successes at catching and
> eradicating your tank of bristles without the use of drugs. This is
> important to me since I have an amazing Coco worm and a few other
> things planned for my reef that will be harmed by the so
> called "wormicides". Ive been using a trap with on and off success,
> actually caught about 1-3/night for the first few nights, and not
> having much success catching the more cautious ones. I think there
> might only be one or two left but not able to coax them out.

The best bait for trapping bristleworms depends on what I have handy at the time 🙂

I found the brine shrimp and sometimes krill (both frozen) work well.
I usually add some to either the trap or the nylons and then take a
small container of water from my reef tank to thaw it out before
putting either the traps or nylons in my tank.

I’ve got two more tricks for ya, First the turkey baster. It doesn’t
really have a lot of suction power. Or at least I’ve never found one
that the ball was on tightly. So I bought a new one and took the ball
off. I wrapped the end with thick clear tape, smae diameter as duct
tape just clear tape. Then when I put the ball back on it was much
tighter giving me much better suction.

Also there is a different type of bulb that is very useful especially
for small worms. They make them for babies noses and you can also get
them anywhere they sell camera equipment. They are used to blow dust
off camera lenses. They are a good size to fit in your hand snugly
and have good suction. Again to make it better there is a small hole
in the bottom on the bulb. I used a piece of a silicone ear plug and
covered the hole. Now I’ve got twice the suction and it works great!!
Eeven though the spout end looks small it really can suck up some
good size worms.

Personally I’m fascinated with the night time world of my tanks. I
completely dewormed my rocks in my sea horse tank. But as for my reef
tank, I kinda like having some brstile worms in there. They really do
clean up a lot of stuff and in tiny little spaces where noone would
ever think would need cleaning. But when I start finding portions of
dead hermit crabs I get a bit cranky. I still can’t kill them though.
I’ve still got the huge one alive and well and am trying to figure
somewhere where I can put him so he can live. I’d love to watch him
closer. I also get a bit cranky when I reach into a tank at night and
don’t watch where I’m reaching. Oops! Got hit pretty hard by a
fireworm one night from a brand new rock. Ended up pulling out three
bristles and got a good sting that lasted 3 days.

Good luck catching your worms, once you start you’ll get hooked on
catching the little monsters 😉
<close quote>

If the population of bristleworms isn’t too bad, they can also be thinned out very effectively simply by carefully winnowing out the largest specimens at night after lights out using a long-handled tweezers. It’s a good idea to wear protective gloves when doing this, since the spicules from these prickly pass are extremely irritating and large specimens can deliver a painful bite.

Hobbyists should be aware that overfeeding can greatly contribute to an overabundance of bristleworms. If you have been scatter feeding or broadcast feeding your seahorses, you can really cut down on the excess Mysis that are available for the bristleworms to scavenge by target feeding your seahorses or training them to eat from an elevated feeding station. Cutting down on their food supply in this manner will naturally reduce the size and number of bristleworms in the aquarium.

Bristleworms can also be eradicated from the aquarium altogether by treating the tank with fenbendazole (brand name Panacur), which is a deworming agent commonly used to treat horses and livestock. It is safe for seahorses and will do a marvelous job of eliminating bristleworms, but it’s best to save this control measure as a last resort for the most severe cases because the fenbendazole can be harmful to live corals and certain snails, and because the massive die off of the entire bristleworms population can result in a dangerous ammonia spike.

Fenbendazole (brand name of Panacur) is an inexpensive anthelmintic agent (dewormer) used for large animals such as horses, and the de-worming granules can be obtained without a prescription from stores that carry agricultural products (e.g., farm and ranch equipment, farming supplies and products, veterinary supplies, livestock and horse supplies, livestock and horse feed) or via the Internet from places such as KV Vet Supply (see link below). The granular form of fenbendazole (horse dewormer granules 22.2%) is preferable to the paste for aquarium use, as the dosage of the granules is easier to regulate (Liisa Coit, pers. com.). It is available in packets of 5.2 grams or 0.18 ounces.

But I would recommend treating your 24-gallon nano tank with fenbendazole, Yvonne, because it also kills many of the polypoid corals and you would not want to lose any of the nice specimens you have in your tank now or that you would like to add to it in the future.

Nor would I recommend using a small arrow crab or two to help control the bristleworms. The arrow crabs are just as likely to take an unhealthy interest in your corals and other sessile invertebrates as they are to chow down on the smaller bristleworms. The peppermint shrimp are perfectly safe in that regard, but not particularly known for preying on bristleworms (they much prefer adaptation rock anemones).

I would recommend you try trapping the bristleworms after dark, as described above. At this point, the bristleworm population in your new tank should be relatively small and manageable, and if you can remove the larger specimens by trapping them, you should be able to control their numbers effectively, Yvonne.

Just don’t freak out about bristleworms and overreact at the sight of a few of the pests. Bristleworms are not public enemy number one — in most instances, they are harmless or even helpful residents of your seahorse tank. But if you want to play it safe, no one here will fault you for trapping the little buggers and terminating them with extreme prejudice.

Best of luck getting the bristleworm population in your seahorse tank under control.

Happy Trails!
Pete Giwojna

Post edited by: Pete Giwojna, at: 2008/05/01 02:59