Any fish left in the main tank runs the risk of carrying the ich. It could easily re-infect the entire tank. I would break it down if you have to, get that goby and be done with it. You will have 2 months to re do the rockwork so it's not pressing to keep everything as is.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.