My school of marble hatchets brought ICH into my planted tank. I been fighting ICH with Quickcure and have used it before it always works.
Quickcure can be bought at Walmart for like 5 bucks, It has Formalin and Malachite green in it.
I Only use the "TETRA DOSAGE" amount, which is 1 drop every 2 gallons vs 1 drop every 1 gallon. Make sure to raise your temperature to help speed up the ICH life and kill it off. Took me 3 days with temp at 80-82 and half dosage 1x a day .
My tank is running DIY CO2 which stays on and no problems with fish breathing. (people say medicen takes Air out of water) Just have a HOB filter running.