Keeping 4ft Blood for friend, first big snake!

[WSmiddy]

Thanks for the info I'll have pic's up soon. Just to be clear its a glass aquarium 4ft long, 1ft wide, and 2ft tall. Ive made a hide for him and he stays in it most the time. I get him out once a day he's been nice so far but breaths hard and has white saliva sometimes at the tip of his mouth. I thought he was hissing but i realize now he's just breathing hard...is that normal?