How Long can a Fish Live with Ich?

How Long can a Fish Live with Ich?



I ask because in the past whenever a Fish of Mine got Ich it Died the Very Next Day.



Then I read to get a UV Sterilizer and to Kill the Ich when it fell of the Fish.



Since getting the UV Sterilizer I have never lost a Fish to Ich.



Sometimes a New Fish would get chased around and Bullied by at least one other Fish and get Ich the Next Day but once the Ich Dropped off them it never re-appeared.



I recently got 2 Fish and they were fine for 2 Weeks.



Nobody in the Tank Bullied them and everyone was Happy and Eating Well.



Then I cleaned the Power Heads because they were covered in Algae and the Flow was severly Diminished.



The very next day one fish got Ich (I guess it was not used to that much Flow).



Then the other new fish got Ich the day after the first one got it.



No big deal I thought.



They will drop the Ich and it will get sucked up into the UV Sterilizer and never come back just like before right.



No.



I check on the Tank around 6 times a day and the Ich has never left these two new fish (All my old Fish are Ich Free by the way).



It has been over 6 Weeks now and they still have Ich.



They both eat well and no fish pick on them either.



Why do they still have Ich?



If it would only drop off them once the UV Sterilizer would kill the Free Floating Ich and this would be over with.



But that has not happened.



Is this like Super Ich or something?



Are there different Strains of Ich?



Will they just live with Ich forever or will they die?



What should I do?