I personally dont think you will see any signs of getting better in a QT. He needs to be in the big tank with plenty of swimming room before he gets better. Smaller tanks like QT`s serve a purpose but once things are OK they need to get back to the big tank. That`s when you`ll see the spot disapear and things get better. This is esp. true with tangs as smaller tanks will stunt the immune system. JMO