No offence mate really, but do some research and learn something before you buy snakes. You should know before you even buy a snake that that is a terrible idea. For starters one of them is a snake eating snake. They are two different species with different requirements. It`s all about stress with snakes, even if they were both Balls Pythons, they would have to be the same size or the much smaller one would spend it`s time terrified. Can you tell when a snake is terrified? Snakes aren`t friendly, snakes just tollerate you, that`s how it is. They never "want to come out and play" they don`t "like to be stroked" They learn to accept you and tollerate you, that`s it. Just because one of your snakes seems gentle, really doesn`t mean you can start mixing species in a tank. Sorry if I sound a little condescending mate, I don`t mean to be but that really is a question you should know the answer to before you even buy a snake.
Here are a few links that you might find helpful.....
Snake-keeping for beginners - by Graham Duke - Helium
Begginers Guide
If you have any more questions, I`m happy to help, I`m sure plenty of people here will be happy to help
Learning about your snakes is essential, fun and very rewarding....
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