June 9 2007,

Bristle worms can be, and usually, are a real problem for reef hobbyists. Indeed, they create havoc in the aquarium, especially when they grow to larger sizes. Bristle worms grow quickly! Real quickly! They feed on anything they can find in the tank and grow to sizes that amaze most hobbyists. This process does not take long either.

Whereas small bristle worms may look really harmless, larger specimens that have grown to sizes of 24 inches or more in length are quite impressive and can cause serious damage. Remember too that the size you see is not necessarily the size of the worm. It may be retracted and look short and thick, but it can stretch itself to a real long size and be very thin. In either case it is a voracious eater.


In addition to feeding on left over food small crustaceans, and detritus from which they extract uneaten parts, bristle worms attack corals and sometimes other animals too (anemones are a good example of the latter). Because of the damage they do, they absolutely need to be physically removed from the aquarium. This can be quite a task and is not as simple at it seems at first as many of you may have found out over time.

Most hobbyists are well aware of this, but just do not know how to go about removing them, or if they do, they are not too sure about all the details of the various methods described in magazines, some as the cure-all for bristle worms (which they often are not). Before being successful many attempts may be necessary (again, as many of you may have found out).

Let me dispel a myth: the small bristle worm traps that are sold in stores will often not work. The trap is either too small or it just does not live up to your expectations. It may trap some real small worms but it will, in the majority of cases, not trap the real large ones, the ones you really need to get rid of as they are the ones that cause most of the damage.

Many methods have been advocated in magazines to rid the aquarium of bristle worms. Most work but often a lot of patience is required before you actually get all the worms out of the aquarium. There are some that work better than others and those are the ones I will describe here. You may have to try several before you actually have the success you wish. Not all methods work in all tanks and with all worms (note that there are many types of bristle and other carnivorous worms).


To find out whether or not you actually have bristle worms in the tank is not always that easy. It is even harder to do so during the day because they hide inside rocks and in crevices. To determine whether any are present, the tank should be looked at during the night, several hours after the aquarium has been in the total dark.

Note also that you need to look at the tank with a colored light. No other light can be used because the worms will re-disappear as soon as regular light is used. They are sensitive to it and go into hiding. When red light is used they remain in the open, where you can see them.

Mind you, when you look at your tank at night you may discover that you have plenty of other animals too, not just bristle and other worms for example. You really have (own) two tanks:

* the one you see during the day
* and the one you see at night (after the lights have been out for several hours).

To see the worms and other animals, the room needs to be totally dark too. Having just the tank lights off is not quite enough. The darker the room is, the better and the more creatures you are likely to see crawling and roaming around the aquarium. Often you had no ideas these were present in your tank. Why? Simply because they are night animals and do not show themselves during the day. When approaching the aquarium with your red light, do so . Do not make brisk movements. Your presence and rapid movements  result in some of the animals you normally do not see during the day to go into hiding. Do everything in slow motion. Play it safe.

Checking for Bristle Worms

As indicated above this can only be done at night. You will rarely see a bristle worm during the day. They hide in rock and in crevices. They hide underneath rock, in the sand, behind rock and in any place where light is low in intensity.

The only way to determine their presence is to use a covered light. You can make a red light out of a flashlight by covering it with a piece of red acetate or very thin plastic material. This can be obtained for Arts and Crafts shops for a minimal amount of money. Tape it to your flashlight. Some package wrapping material is red too and can be used as well.

Once you have done all this, you are now ready to look at the tank in detail. Inspect all areas of the aquarium. Indeed, some of the live forms you may discover (in addition to Bristle Worms, are real small). You need to do so in total darkness and several hours after the lights have gone off. Their should be no light in the room what so ever. It is a good idea to close your curtains or blinds too.

Inspecting the aquarium will show you that there are many more life in your aquarium than you actually imaged. Some of that life may be bristle worms or other undesirable animals. Some may be desirable and some may not be. I can not decide on that without knowing what exactly it is that you have. Descriptions over the phone usually do not help a lot in identifying such animals. It is too hard to describe exactly what you have. A photo sent to me though will allow me to give you an identification. A Polaroid shot is usually plenty, a regular photo will do too of course. You are welcome to avail yourself of this service we offer at no cost.

This, now, leads us to the actual removal process and the methods that you can employ to do so. There are several, as I indicated earlier. I will cover the ones that hobbyists seem to have the most success with. They are all geared to setting up some kind of a trap, but the traps themselves differ and what is placed inside them may be different as well. I really prefer to make my own, as you will read later. This is not difficult at all and makes the whole process really inexpensive.

Try one of the methods and if you are not successful at removing the undesirable animals try one of the others. What is really important in this whole process is patience. Do not give up too soon deciding that you are not able to remove the worms and other unwanted animals. You will eventually succeed but you must pursue the endeavor. If you give up too soon you have lost all you have accomplished as the worms will start reproducing. They do so rapidly too (just as they grow rapidly).


Trapping the Worms and other Undesirables

Let us first discuss and list what kind of traps for worms and other animals you can set up and use. That will get us started, and you can decide which one you want to choose to start your first attempt at catching what you want to get out of your aquarium.

If the trap you select at first does not work, go to another type and continue you endeavor to remove the worms and whatever other undesirable animals you may have seen in the tank during your night inspection.

Below are various kinds of traps, from rudimentary to sophisticated ones. Choose the one that you think suits your purpose best (look at the cost too). Some you can make yourself, others are sold in stores and are prefabricated by manufacturers. Pet Stores and Mail Order places will have them available.

Types and Kinds of Traps

* Plastic or acrylic traps with a small opening through which the bristle worm (in this case) can get in but not out. These are commonly found in pet stores or through other outlets.
* Plastic or acrylic trap with large door. As soon as anything enters the trap, the sliding opening (door) to it closes (drops down) and whatever got in is trapped as it can no longer get out.
* Small plastic or acrylic containers sold as bristle worm traps in many pet stores and other pet supply outlets. I have found and other hobbyists have told me that they do not really work all that well if at all. I am not saying that they are useless but, it is my opinion that you can do better as we shall see.
* Home made traps (we will go into these a little later). These are the ones I prefer. These also seem to be the ones that hobbyists have the most success with.
* Fancy traps that can catch not only worms but a number of other animals as well (often they catch what you don’t want to catch).
* Traps that you hang inside the aquarium.

All the traps described work on the principle that they are placed in the aquarium, in the area where you suspect there may be a worm (or several of them), and leave the trap there during the night (or for several nights in a row), after you have placed some food stuff in the trap to attract the bristle worm(s). The key then is to find the right kind of trap, the one that seems to do the best job at trapping the bristle worms and preventing them from getting out of the trap. Although the commercial models may work and may remove some of the undesirable animals, including bristle worms, I find that hobbyists seem to get the best results with home made models that cost very little and appear to be more effective than the more expensive ones. Why they are more effective has to do with their design and with the fact that they often can be adjusted by the hobbyists according to what he or she wants to trap (as we shall see in the next section).

The way I suggest you trap worms and other animals you do not want, is to use such a home made model. I personally have nothing against the commercial ones but find the home made ones to work better. I will describe the process on how to build such a model below.

You can, of course, use some of the models described above and place food in them to attract the worms. That method may or may not work as I indicated. If the method you are now using that employs such a device does not work, meaning that it does not trap anything, try the home made models. In my experience and that of many others, those are the ones hobbyists are having the most success rate with.

Home Made Models and how to Use them

Various type of home made models can be made. The difference has mostly to do with their size. You may want to start off with a small model and if that does not seem to work, upgrade to a larger one. Since you will be using very inexpensive materials (actually mostly food jars) the cost of changing is just about zero.

Another manner in which to change and see if you can trap the animals you want out of the aquarium, is to change the food stuff you place inside the container that is used as the trap. That often is better than making an new trap. Sometimes the type of food has a great deal to do with whether or not worms and other animals will enter the trap you set up.

If you have observed your aquarium at night, which you should have done, and know the approximate location (hiding space) of the worm(s), that is where you should place the trap, or at least as close to that area as you can. If there are different areas, you would want to move the trap around as you keep catching worms.

Note that besides bristle worms you may have noticed that your tank contains a Mantis Shrimp. The method used to catch it is the same as the one described for the worms. The only difference may be that you need to enlarge the holes in the container you use as a trap, to match the size of the shrimp you need to catch.

To make the trap, use a small plastic food container that has a lid. The container should be opaque not transparent. You do not want the animal you want to catch to be able to see the food inside. You want it to have to crawl to the top of the container and then in the container to get to the food. The smell of the food is what should attract it and make it do so. When the right kind of food is used, the animal will.

What to put in the Trap for best Results?

The choice of foods I recommend you place in the traps are:

* Shrimp meat (cooked)
* Scallop meat (raw)
* Fish roe (raw)
* Mussel meat (raw)
* Clam meat (raw)
* Pieces of edible fish such as fish for human consumption (raw)
* All these items are bought at a fish market, not at a pet store
* You can, of course, place several kinds of food in the container (trap).
* I do not favor brine shrimp. They do not seem to attract the worms and shrimp or other animals you want to get out of the tank.
* Frozen fish foods, bought at pet stores, do not seem to produce too good results either. What I am referring to is the commercially available frozen foods that you use to feed your fish.
* Stick with the ones listed above and your chances for success will be greatly enhanced. All fish markets carry that kind of food stuff. Fish roe may be a little harder to get but you can order it and ask the owner to keep it for you rather than throw it away, which is what they often do.

The size of the pieces of food that you place inside the trap need to be small but not minuscule, remember you are trying to catch bristle worms. Too large pieces of food do not produce the result you and I are looking for. You can cut the fish food you use up (whichever of the above you use) with a knife, or put it in a blender and chop it up. Do not make the pieces too small either (no mush please). When using a blender, set it so the breaking up does not go as far as making a paste of the food. When using a blender, a milky watery solution usually develops at the same time. Do not use it. It is laden with phosphates and will pollute your aquariums water. You will then have to spend money to clean up the water before green filamentous and/or slimy algae start growing. Do not add pollutants to the tank that you later need to spend money on removing. You can avoid doing so by not adding the liquid.

Place a small amount of food in the container and make sure it remains at the bottom. By small I mean pea size to two pea size maximum. Do not put more and if you do not catch bristle worms in the first 48 hours replace the food with fresh one. If you do not, the food will start to decay and pollute the water. As a matter of rule, the food should be changed every 48 hours at least. Changing it more frequently is fine of course.

How to Fabricate the Trap

* Use a kitchen type container or a used food container made out of plastic. Make sure you have lid for the container. The container needs to be opaque. I have outlined this before. After you have added the food to the trap, lower the container in the water and let it fill with water.
* Place it in the area where you think the bristle worm or whatever else you need to trap resides or hides.
* Before doing this though you need to prepare the trap:
* In the lid make an X shaped cut with a razor blade.
* The size of the X should be just smaller than the thickness of the worm, or Mantis shrimp, or whatever else you are trying to catch.
* Gauge the thickness carefully as the size of the opening in the lid needs to be slightly smaller than the size of the animal you are trying to trap. This is probably the only difficult part in the whole process. Remember that worms can make themselves real thin.
* Push the four pieces of plastic that are loose as a result of the X cut inwards, at about a 45 degree angle. You can do this with your fingers or a tool. They should remain in that position. This is important (see below).
* This allows the animal you want to trap to get in easily, but makes it hard for the animal to get back out. As it tries to get out, the pieces you pushed in will want to come back up as a result of the pressure the animal exerts on them. That is what makes it hard for the animal to get back out of the trap.
* Now all you need is patience.
* Remember that you may not catch anything the first day and that you need to persevere.
* Keep at it and you will catch what you are after even if it takes longer than you expected. The key is not to give up.


If the container/trap you use is not working -meaning if you do not catch anything- change the food you put place in it and make the cut in the lid either smaller or larger, depending on what you are trying to catch. Sometimes the cut is too large and the worm or other animal gets back out, sometimes it is too small and the animal cannot get in. Adjust the size of the cut and eventually you will catch what you are after.


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