I am not a ball python expert or anything, but I can tell you what my experience has been. I have two Balls, one of which is a quite nasty and nippy subadult female. (this is NOT normal! Please don't be turned off by BPs, they're not nasty normally.) I have found that whether I feed her in her cage or not, she is still nippy and suspicious when I go in to pick her up. I don't really know why she's like this, but my adult male BP has never struck at me. I do not remove him form the cage to feed. He seems to know the difference between me and the rats I give him. So I would say that it isn't necessary to use a seperte container, unless you had some kind of elaborate setup where the substrate could somehow become lodged in the snake's mouth and get swallowed.
I would definately make sure the BP you're getting has an easygoing temperament. I started out with a nippy gal, and it would have been much easier if I'd gotten my nice male first. But I would never get rid of her based on temperament; she's got character!One strong recommendation; when removing a BP from its cage for cleaning or handling, never grab for the head or neck! Pick it up from the part that's not visible to it, and you should never get bitten, even accidentally.
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*~Ginevive~*