Today I turned my light on a noticed my goldfish have Ich. They didn’t show signs of it yesterday. I have two small comet goldfish and one rubber lip pleco in my tank of 20 gallons which I know is too small for them, but that’s besides the issue right now. I know I can go to petsmart and get something to treat it. What else should I be doing? I can’t see any signs of it on my pleco. What steps do I need to take? I’ve had them for some months now and the pleco is new to the tank so that’s the only way I figure they could have gotten it.