IMO, if the fish are healthy and unstressed (as they should be in any tank) they will handle the ich and it won't get out of control. Your fish is new, and would have been stressed during his acclimation to the new tank, hence why he got 'Ich'. I personally wouldn't worry about him, keep him healthy and it will go away.
It seems that people freak right out when they see this, but it doesn't seem to hurt the fish much as long as everything else is in good shape... by this I mean great water quality, regular water changes, a varied and healthy diet appropriate to the species of fish you are keeping, and minimal stress factors (aggression and bullying, stable water conditions, a regular photoperiod, etc.). The fish recover from the stress, fight off the infection, and everything is good. IMO again, many people heavily overstock their tanks in terms of fish, which directly correlates to maintenance on the tank, and when that maintenance isn't performed once for one reason or another, the fish get sick because of overcrowding and poor water quality. Healthy, happy fish = fish that don't get sick from minor infections, or are strong enough to fight them.
Try not to overstock, and remember that large fish eat more and create more waste. Other than that, as was said before, you can quarantine everything for 6 weeks after clearing your tank completely of your current Ich problem...
My personal experience with ich is from freshwater fish though, so take what I've said with a grain of salt.
