Hi guys! So I have a betta fish in a 10 gallon tank and there has been a strange film on the top of his tank. First it was rainbow/oily like then it turned cloudy and white. So i tried to fix the situation by adding an air stone to create agitation. It definitely worked but he seems stressed by it. I am trying to get a sponge filter but i cannot get one right now. What is this film and is it dangerous?