With due respect to all the above mentioned suggestions- the easiest way to get rid of the ich - even on cardinals- is to use good old QUICK CURE. It says use a half-dose for tetras, but I have dealt with this countless times of the years of doing maintenance for clients and I can assure a 2/3 the recommended dose will knock out any ich within 3-4 days. It is absolutely harmless to the plants, and the blue color is kind of cool for the 30 min. or so it lasts. I have done close to a full dose on cardinals for first day or so with no ill-effects also. I have never lost shrimp either. Just recently, in fact, I had to dose a tank for about 8 days at 2/3 recommended dosage and all shrimp are totally fine.