I have been noticeing a rainbow colored film on the top of my tank. It looks like the oil you would see spilled on pavement. Should I be worried? Im cleaning the tank tonight im just wondering what could be causing this?
It sounds like it's just the normal slime that will build up on stagnant water. As long as you're keeping up with water chances, which I'm sure you are, it's nothing to worry about in regards to your betta's health. However, if it really bothers you, you can put a filter or air stone in the water on very low, just enough to keep the water moving a bit to keep the sliminess from building up.