"Trophont: This is the obvious stage, when you can usually see the white spots on your fish. In this stage, the parasite has made itself at home under the epithelium of your fish and encysted itself; the white spots you see aren?t actually the parasites themselves, but the fish?s biological response to the parasite that has burrowed into its skin. It?s really made of mucus and proteins that the fish has produced in an effort to rid themselves of the irritation. In this stage it is NOT susceptible to medications, both because it has encysted itself and the mucus/proteins the fish has produced protect it. "
"The most popular form of treatment is medications.
The majority of Ich meds contain one or more of the following: Malachite Green, Copper Sulfate, Formulin, or Potassium Permanganate. All the meds are poisons, malachite being the deadliest; the school of thought is the fish are less susceptible to the dangers then the parasites. However, some fish are more susceptible to meds, specifically scaleless fish such as plecos and loaches and one needs to be careful in dosing. It is important, when choosing an Ich med which will be used in a tank containing scaleless fish, to either find one which is formulated for scaleless fish or to half dose for twice as long. Do NOT use these medications on invertebrates such as shrimp or crabs as it will kill them. Either remove them from the tank or chose another treatment. Never use a copper treatment in the tank if there is inverts; it is near impossible to remove from the substrate.
Do a water change prior to starting treatment and remove the carbon from the filter media; not the entire filter. If the carbon is part of the filter cartridge, make a slit in the side of the filter media and remove the carbon.
Be aware meds will most likely destroy the nitrifying bacterial colonies. Be prepared to measure ammonia and nitrite levels, and reduce the levels if necessary, by water changes or ammonia/nitrite reducers (this is the only time you?ll see me recommend their use!). Water changes likely will affect levels of meds in the tank, and you may need to adjust doses to keep the meds at the levels needed to kill the theronts.
Once treatment is finished, you?ll need to remove the meds from the water. Best way to do this is to run fresh activated carbon in your filter for a couple of days.
** Do note, the directions on the meds are generic; if you remember from the earlier discussion ich has a life cycle with only one stage susceptible to meds. Do not follow the directions when it comes to length of dosing times as some will claim to eradicate Ich in as little as one dose. The first treatment will only kill a percentage of the parasites (remember the Ich life cycle). It?s better to continue treatment till 3 days after seeing the last white spot on your fish; this way you can be fairly sure you have eradicated all the parasites. "
I am sure you will get better advice from other members but I have also heard that copper in a QT
is an effective treatment.