Hey there...

Quick question on a Beta fish we bought for my son last Xmas. He was eating and doing well up to a month ago. We noticed what looks like an oil sheen that forms at the top of his water and his eating has been almost non existent. I've tried to change the water a couple of times but the sheen comes back. For the record, he's in a small bowl w/ no filter or heater. I think I read somewhere where the oil sheen could be a result of oil from your hands if you touch the food or water. If true, I'm wondering why all of a sudden it's happening. Any ideas?