Hyposalinity
Hyposalinity treatment is probably the most successful and least stressful treatment, if done properly. Unfortunately, this can't be done in a reef tank. However, it can be done in a Marine Fish Only tank, with a caveat or two.
Hyposalinity is treatment by lowering the salinity of saltwater, to a level that it will kill the parasite, but NOT kill the fish. In fact, lowering salinity eases a fishes ability to "respire," and increases oxygens ability to mix with the water.
Changes in salinity do need to be done correctly, as to not stress the fish. Lowering the salinity can be done quicker than raising the salinity. Typically the salinity can be dropped from 1.025 to 1.009 in a matter of a couple of days, without negatively effecting the fish. However, once treatment is over, the salinity should be raised back up to 1.025 slower (over the period of a week.) Treatment needs to be done for a period of 6-8 weeks, OR at least 2 weeks after all visible signs of Ich are gone. At that point, salinity can be slowly raised, over a 1 week period. During this same time, the display tank must remain "fallow," or fishless. Without any Fish Hosts, the Ich parasite will die.
1.009 has been shown to be the level where Ich can no longer survive, without negatively effecting the fish. Again, this cannot be done in a reef tank, as motile and immotile inverts will die. In a Fish Only system, this can be done, however, beneficial bacteria, micro fauna, micro flora, amphipods, copepods, etc. will perish. Those things will re-populate, over time.
Hyposalinity is best done in an established QT tank.
