Originally Posted by
Love My Tank
http:///forum/post/3084967
Are they bad?
Here is the info from the DR.
Quote as follows;
Rust Brown Flatworm
The first and most common type of flatworm can become a nuisance quickly in the home aquarium. These organisms are tan, brown or rust colored with a red dot, and reach a size of up to 1/4" in length. They are oval and slightly elongated with two tail-like appendages at their posterior. This brown flatworm has been identified as Convolutriloba retrogemma, and will proliferate rapidly in aquariums with elevated nutrient levels. The populations of these pests can increase to a point where they will actually perch on corals, and block the light from reaching the corals' tissue. Some experts believe that the flatworms actually feed on the zooxanthellae from coral tissue, thus damaging the corals themselves.
Symptoms & Signs
The Rust Brown Flatworm can be seen on top of corals, and normally in areas of low flow in the reef aquarium. The Acropora-Eating Flatworm can be recognized by the rapid tissue loss in certain colonies of Acropora, and their presence will be known by the gold to brown egg masses that they leave behind on the bare coral skeletons.
Treatment
The best way of controlling flatworms is by prevention. Maintaining low nutrient levels in the aquarium with the use of carbon and aggressive protein skimming, along with increased water flow will help to reduce the populations of these pests. Proper quarantine of new specimens, and all aquatic life before they are placed in the display aquarium will keep the initial introduction of flatworms to a minimum. Blue Velvet Nudibranch
* Natural means of control include: Wrasse of the genus Pseudocheilinus, such as the Six Line Wrasse (P. hexataenia), Halichoeres Wrasse, such as Yellow Wrasse (H. chrysus), Macropharyngodon Wrasse such as the numerous Leopard Wrasse (Macropharyngodon sp.), and Dragonets such as the Spotted Mandarin (Synchiropus picturatus). The Blue Velvet Nudibranch (Chelidonura varians) is very effective at consuming flatworms in the aquarium, but is very sensitive to changes in water chemistry and has a short life expectancy in the home aquarium.
* Although the species mentioned above will consume flatworms, they may not feed on all of the different species that inhabit the aquarium, nor will they typically rid the aquarium completely. Also be sure that your aquarium is appropriate for the fish, as some of the species do have special requirements and increased care levels in the home aquarium.
* Another method of removing flatworms from an infected colony is by performing a brief freshwater bath or dip. Flatworms are very sensitive to salinity changes; by dipping the colony in dechlorinated freshwater for 5 to 10 seconds and then shaking the colony while submerged in the bath of freshwater, will cause the worms to lose their grip and fall to the bottom of the container. Be sure the freshwater has the same temperature and pH as the aquarium's water in order to reduce the amount of stress on the colony.
* The last method involves manual removal. Siphoning seems to work the best, as the flatworms do not keep a very strong grip on the colony. A small diameter airline tubing works very well for soft leather coral colonies and some species of mushrooms. Be careful not to damage the coral with too strong of a siphon. For the more delicate mushrooms and LPS corals, small syringes work very well. It is possible to get the syringe very close to the flatworm and gently draw the worm into the syringe without harming the coral.
With severe infestations, you may have to employ a combination of all methods mentioned above in order to eliminate or even control the populations of these pests.
Hope this does not scare you too much and I hope it helps. May of us have had them to deal with over time.