What all does the 150 have in it as far as substrate, rock, etc.. How long has it been set up? You really need to try to test for ammonia, nitrite and nitrates.
What are you using to measure the salinity. Did the fish have ich as a reason for doing hyposalinity? Is the eye just cloudy or is it also protruding?
Is the fish eating at all or has it been eating for you?
Let's find out the water parameters first.
The color fade/blotchiness and even the cloudy eye can be secondary problems to ich.
Also, changing out 10 gallons in a 150 is not going to do anything. You need to perform a substantial water change using aged, aerated saltwater. 30 gallons is not too much, and more may be needed if there is an ammonia or nitrite reading.
Can you get some Nitrofurazone? (sold as FuracynT) It works well on internal and external infections and is well absorbed by most fish. One of the better antibiotics IMO. You need to dim the lights as it is inactivated by light. It also has the benefit of some anti parasitic action.
