A pic would help. Hippos are susceptible to ich more so than the other tang species.
Do you see it rubbing against the rocks a lot?
Of course its Ich. Keep feeding him. No stress. Use garlic. Raise temp a bit
Dude it's fine. People are going to flame me for this, (but I really don't care because I have hours of field research to back it up) ich will always be existent in fish and will present itself when he/she isn't feeling well. It's kind of like our common cold and definitely "fixable" if you catch it at the right time-- meaning the fish is still eating. Best way is to just boost the immune system and get the fish used to the "routine" of your tank.
If he's eating it's fine. You can use real garlic or garlic extreme it doesn't matter.