By J. Charles Delbeek
Q. I have a 15-gallon mini-reef aquarium in which there has been a recent outbreak of a bristle-type worm. These worms are very small (2 to 2.5 millimeters long and 1 to 2 millimeters wide). They are usually pink, or pink on the ends and dark (almost black) in the middle. They have small bristles/spines, no more than half a millimeter long all over their bodies. They reproduce very quickly. I can't remove them with tweezers fast enough to deplete their populations!
I have two blue crocea clams, an open brain coral, many mushroom polyps and a few feather duster worms in my aquarium. How do I get rid of these bristleworms? Are they dangerous to my clams? Is there a particular fish or shrimp that will eat these worms, if in fact they are dangerous?
A. These small worms are basically harmless and can actually be helpful for a tank by feeding on and breaking down detritus. Moving through the substrate, they act like earthworms, loosening the substrate and improving circulation, while their metabolic activities contribute to helpful bacterial populations. If their numbers increase greatly, they can become rather unsightly. It is possible that large numbers of these small worms can irritate the clams if they get between the valves and the mantle or between the substrate and the byssal opening of the clam.
Removal is relatively simple. In a tank as small as yours you could easily siphon out the substrate and rinse out the worms. You can also place pieces of shrimp inside a section of nylon stocking and put this into the tank. The worms will swarm over the bait and their bristles will become entangled in the nylon mesh. It is then a simple matter to remove the stocking and rinse off the worms. Several fish will feed on these worms, such as pseudochromids (dottybacks) and small wrasses.