i would advise against that strongly. there are a few reasons this should not be gone.
1if you feed him to the point of exploding he will bloat and might be harmed
2it is never good to leave a fish without food for a whole week! 1 day is another matter but a week....
3 this can easily be solved
is there anyone you know that could make it to your dorm even once a day to feed your
Oscar?
if not then you could always buy one of those machines that will add the food for you. dont say its too much money because it will keep your pet alive and then you will have it for other times when you go on vacation.
whatever you decide please dont leave your fish alone without food for a whole week.