Don't forget that you still have separate lives outside of your relationship. Though I don't recommend living together your first year or so of college (way too risky), if you do choose to live with him, your stuff will still be yours and his stuff will still be his, for the most part. It's not as if once you are together, everything is universally owned and thus you cannot own a snake because he doesn't want to.

For example, my boyfriend and I both have different pets. I keep snakes, he keeps fish and geckos. We like the others' pets, but the responsibilities are divided - I take care of my own pets, he takes care of his. That should be understood when you obtain the pet. So really, your boyfriend would not have to come into any contact with the snake if he didn't want to, because the pet is yours, and he wouldn't have any responsibilities of taking care of it. The snake tank or tub would just be an object in the room that doesn't belong to him, if that is how he wants to see it.

In conclusion, since he is not phobic of snakes, this really does seem to be a control issue to me - you haven't given a solid reason why he refuses to live with a small inconspicuous tub or tank that happens to contain an animal.