I've had people ask me how I deal with ich in my tank. Apparently they think I have a secret. I have bought all kinds of fish over the years, but you never hear about ich issues. Yet, based on posts by others it's like the majority of you are constantly suffering from this problem.
First of all, where do you buy your fish? I prefer to shop locally when I can, so I can see the fish in person and inspect their health. If I see spots, I'll pass. And keep in mind if multiple tanks shared a common sump, the fish in the neighboring tank that looks healthy could in fact be infected as well, even if they aren't displaying anything at the moment.
All my new acquisitions get a Safety Stop bath, which is a double bath process that takes about 2 hours to complete. I have a video about it on my youtube channel if you want to know more.
I feed my fish quite a bit, and endeavor to maintain stable water with minimal stress in the tank. In all the years I've been in the hobby, only one Yellow tang broke out with ich and it was dead within 24 hours flat. That was when I had my 55g reef running; I had a large blue atlantic tang that came with that tank and he harassed that brand new yellow, which essentially terrified the fish into a corner. I was planning to move it into a separate tank the next morning, but when I got up it was already dead. That incident was so fast. But none of the fish in that tank broke out in ich ever.
So that's the answer.
Originally I wanted to post a joke about this topic, but my desire to share useful information superseded that plan. So I will wrap this up with my humor now:
If you want to help a ich-covered fish, it's easy. Catch it and drop it inside the protein skimmer. That bubble wash will clean off any ich in no time. If you look at this picture of my skimmer, there are four snowflake clowns getting polished now and in another hour I'll pull them out. You can see all the ich came off. And it will end up in the collection cup. I hope this helps.