aszbinka: we need either more description of said white thing or pictures
braden: I live in Florida too, doesn't mean the tank water is 80 degrees. If your room temperature is lower than 80, it will decline. I'm assuming you have air conditioning. You need to get a little $3 thermometer at the pet store and check the temp, if its below 76 he could just be freezing, that's why he doesn't move. Tropical fish. Cold waters slow down their metabolism and lower their immune system. In over a month and he's not skinny? I've heard of a fish lasting 2 weeks without food but not a month.