Like I've said before Mina, I'd get Dax sexed LOL. It could just be a stage but I suspect it's those medium rats and just Dax fasting to self-regulate his (or her) weight. I know most of our females act quite different during that teenage angst Judy mentioned. Changing their feeding habits or style, become more or less able to be handled, hiss when they usually don't, that sort of thing. Seems to pass as they mature into the lovely bigger females but for awhile it's like they are a different snake.