I use to have white spot/ick every other month and is effecting my hippo tang badly.
I solve that by putting a small piece of garlic and grind them together with all the fresh cockles, fish meat and prawns into a paste. A special recipe for the fish.
It have been a year and a half and I don't have any white spot breakout.
My hippo survive the first 2 outbreak. From 3" inch size, he is now 7 inch.