my school just allowed fish, although they would look the other way on turtles and other such things which also live in aquariums. One girl had the cutest little tiny turtle!
But that didn't stop people from having other pets. One guy had a ferret for a while, and a couple of girls took care of their friend's puppy for like a week while he was out of town.
I had two fish while I lived in the dorms, but I could never keep them alive longer than a couple months, so I stopped getting them.
Most people here live in apartments near, but off, campus and many of those places allow pets so I know alot of people who have cats and dogs. One of my friends has guinea pigs. My place doesn't allow pets though, unfortunately. I miss my cats at home!