I just noticed that my 50 gallon tank with cardinals & 2 plecos is infected with ich. My real problem is that the 2 plecos are L 46 Zebra plecos. I can see the ich on 3 or 4 of the cardinals but not on my zebras. The temp. in the tank is 84 degrees. Are plecos a problem to treat my ich infested tank? Please advise. Thanks in advance.