Not sure on the size of the tank they get to a decent size, but – Red tailed rat snake,Gonyosoma_oxycephalum - watch the teeth though.
They spread their neck like a cobra but the other way round. top to bottom. and soooo pretty.
Edit: Ps not venomous although they might look it for other members that may not know,
Had these years ago, awesome. Take a lot of work if you want to handle though in my experience
Now i want them again… Nice display snake
Edit 2: I am sold, getting a pair and a display tank