I've had this 1 inch Foxface for a month now. Perfectly healthy a week ago. He started to act weird lately. He would law down on the sand and place his body against the glass. When I'm feeding he comes up for the food and acts all normal. When he goes down he stays yellow and doesn't change color. Is he okay or is there something wrong? I don't have a test kit ATM but I do water changes every 2 weeks or so. I could see him breathe somewhat heavily but not so much that he doesn't have air. Any advice? Much appreciated!