can take as long as 30 days to die off completely. There is also the chance this is not ich. Has the infestation on the fish lessened at all or is it still as dense as at the beginning of the treatment? How often are you testing the salinity? What is the alk
The conditions of the fins/scales could easily be from secondary infection. First step would be a series of large water changes with well aged SW
and feeding with vitamin fortified foods soaked at every feeding time. Be sure they are high in [acronym="Highly Unsaturated Fatty Acid"]HUFA
[/acronym]. Since you opted to treat in the main tank, antibiotic should not be used so hopefully it will not come to that.