Just like to ask will the Ich survive in the Tank if the fishes left show no sign of infestation despite the infection of one fish? Does this mean the Ich will die becuase the cannot attach themselves to the remaining Fish ( potential hosts)?
Not necessarily. Your remaining fish may be showing no signs of ich because the life cycle has not gone completely around again. The normal life cycle for SW
ich seems to be a month or so. This is probably actually longer than the cycle, but this gives one a good margin of error.
Some fish have an innate immunity to the parasite. But these seem to be few and far between. You can either hope for the best for the remaining fish, or move them to quarantine.