Another idea for heating would be a heat pad. Not sure how you would go about using it... Im sure someone here has used a heat pad and they might know.
Well speaking from a reptile point of view, most sticky heat pads can easily(and come with instructions for) mounting on the sides of the tank. This would probably work since it shouldnt be seen as a fire hazard.
Don't be miss negative. IMO getting a fish can keeps a student enteraining while studying for exams. Alot of us have fish tank in their dorm rooms. To my knowledge, nobody try to feed the fishes with crap or beer in the dorms anyways.