There are only two proven methods to kill ich; hyposalinity and copper treatment. Some fish, such as tangs or butterflies, are very sensitive to copper. Hyposalinity is the preferred treatment. Niether treatment can be done with inverts, and medication should NEVER be added to a display. A quarantine tank will be needed. Whether you should remove the LR and inverts or remove the fish depends on how much of either you have and if the QT tank is cycled.