(FYI)
Home Bristle Worm Traps and how to Use them
Albert J. Thiel
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. 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 aquarium's water. You will then have to spend money to clean up the water before green filamentous and/or slimy algae start growing. Don't 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.
controlling bristleworms+aiptaisa 
