I have a 55 gallon aquarium with four goldfish and one pleco. Several days ago I found Ich on my fish. I quickly treated the tank with salt on the first day. The second or third day I was able to get malachite green for treatment. Then I got a heater for the tank. I know goldfish get more stressed in warmer temps so the tank is still at 78 to 80 degrees. I know at these temps Ich can still multiply. However my goldfish have seem to dropped all of their ich parasites. The pleco is the only one affected at this time. He still has a lot too. I've treated my tank twice in the last 48 hours with malachite green at half the dosage because I really don't want to harm my fish and the goldies are already stressing. Without removing the pleco from the tank I've been treating how can I get him better without harming him and the other fish?