id like to personally say that out of the 4 options, id recommend the hypo treatment... chemical treatment is hit or miss (just killed 2 of my fish, including my blue fish angel) and its almost impossible to tell if it actually kills off the problem. fw
dips are equally dangerous, but in a different manner. You're talking about placing a saltwater fish in non-saltwater until the fish shows signs of stress. to me, stressing out a fish with ich is only speeding up the problem (not what we want). id just gradually drop the salinity down and hold it there for a few weeks. but be careful, the lower you drop the salinity, the lower your kH
will drop, causing your ph to possibly swing.