I have a 15 gallon tank that has been set up for about 5 months. All I have in it in the moment is 2 female platys and one male and 3 baby mollys(I traded their mom in, I just wanted to raise them till they are big enough to donate to my LFS). I do a 30% water change about every week and a half to two weeks. They get a variety of healthy freeze dried and flake food. I have tested my water for nitrates, nitrites, hardness, alkalinity,pH, and ammonia and it was all well in the normal to ideal levels. It all started about 4 days ago when I noticed my male platy rubbing against a glass rock in the tank. He did it in such a playful nature that I wasn't sure if he had a problem. Then about 2 days ago I noticed everyone but 1 female platy was itching. I called my LFS and asked them about it and they asked if I could see any signs of ich, fungus, etc. and I said no, so they just told me to keep an eye on it. However when I got home last night 2 of the platys and 1 molly were basically laying on the gravel and breathing more heavily. They seem extremely lethargic and it seems to take all their energy to swim, though they are all still eating. I have looked these fish up and down and cannot find a single thing on them that would indicate what their illness is. I read that ich can just be in a fishes gills without white spots appearing, is this true? They certainly seem to have the symptoms of ich, should I begin to treat them? I would be super grateful for any advice. I want to begin treatment asap, but dont want to do anything that will make them worse.