Wow, that is a lot of tangs in your tank. How will you handle that bio-load in a few years when all of them have grown much larger? I am genuinely curious because I am stocking my first tank over 120g and based on many of the stocking plans I am reading on these forums, I am under-stocking. Everything I have read on this forum leads me to believe that PBT won't survive long term in your tank because of the ich. Maybe I am wrong, I have not kept one myself yet, but I have qt every fish since I think there is a possibility I may add one.