Suppose that is an option but I would go to walmart or LFS and invest in a quarantine/hospital tank for future use. On the downside, if that really is ich that the tang has, there is a decent possibility that your entire DT has no been infected with ich unfortunately. I just got done with a bout with ich and my medication/quarantine/fallow time and I'm Qt'ing from here on out. I used a small HOB filter and took a filter sponge from my other tank for some good bacteria, used Cupramine by Seachem to treat for 4 weeks while monitoring the copper levels and doing water changes and then observation for 4 weeks to remove the copper through water changes and a regular carbon filter as well. I did not use live rock because that throws off the readings and makes the rock unusable from absorbing the copper.