The first time I had ich, I went old fashioned salt and heat. The ich was never serious, maybe 1 or 2 dots on a fish here or there out of tons of fish... it actually took a long time for it to go away, the heat was high but not as much salt because I didn't want to hurt the catfish. I wanna say maybe 1 or 2 months. Not sure why it took so long.
The 2nd time, same thing..only a few spots here and there and I used Ich Attack... and it got better a lot faster. I didnt dose properly, I just glugged it right in the tank. Just my experience. One bottle split between a 20 and a 72 tank, and I didnt get to finish the whole bottle before it went away. Did not raise the heat either.