I never had to deal with ich until some ghost shrimp brought it in to one of my tanks a couple of months ago. I made the mistake of pouring a little of the water from their sack into my aquarium, and I'm guessing that's how it got there... anyway, I noticed it when my oscar had just two spots, and got rid of it in three days
Good news for cory lovers! Our cute little fish are resistant to ich and very rarely get it.
One of the main ways to help them spawn is, in fact, to lower the temperature in their breeding tank, which is something that causes an outbreak of ich in other fish.
Our cute little fish are resistant to ich and very rarely get it. 
