I got up this morning and went to check on my fish and feed them, and couldn't find one for a while. One of my platys was hiding way up under a fake coral cave and I actually had to pick the decoration up to find him. I was looking all around the tank to see if he had somehow jumped out, that's how hard he was to find. Anyways, this is new. They are usually greeting me at the window as I walk in each morning waiting for food. He is still eating, but he just seems lethargic. I've noticed him hanging around the top in what looks like a gulping for air behavior. Right now he is just kind of hanging around the bottom, not really swimming much, while all of the other fish are very active. My first thought was the water. I did a PWC sunday, everything went well. I checked for ammonia earlier. The API test kit I have looked like it may have had a slight yellow/green tint to the water, but it was so close to the 0 reading that it was hard for me to tell. I went ahead an put in some ammo-lock just to be safe. I am going to test the other parameters soon, but up until today my readings have all been 0/0/normal (don't remember exactly). I have live plants and the tank is cycled, so I'm not sure what the issue could be. Any ideas?