Today my bettas each made their first bubble nest. I have owned them for over a month and they have never made one. They are in a divide 5 gallon tank and i am ve4ry good about the water changes. Today i noticed on the surface of the water was an almost glossy film over the top and was sort of reflecting a rainbow almost like gasoline in a puddle. I know its not gasoline or anything like that because nothing has been spilled. I was wondering if this was something natural im unaware of or what. Any help or knowledge would be awesome!!