xo_Kathy,
As a former rush chair, I feel your pain! I think the goldfish would have looked amazing. Too bad.
Delta Gamma on my campus were known for using goldfish all through out rush. They really played up the nautical theme, they wore adorable sailor hats the first night and always had anchors everywhere. They had little ponds full of goldfish just like the one you describe, and for preference their centerpieces were goldfish bowls instead of flowers. We never thought twice about "reporting" them for using "live animals." The only concern anyone ever had was that the golfish had good homes after their Rush duties were over. And that was well taken care of, every DG I knew had an aquarium with former Rush goldfish. It was their bid day gift!
Also, did any other rush chairs exchange rush gifts with the other rush chairs on campus? It's not done on the campuses I've advised, but when I was rush chair we each gave each other gifts every night. The gifts got bigger and more formal as the week went on, the first night was cookies, the second night, bubble bath, etc... I still remember how delicous the Tri -Delt sugar cookies were, (which were in the shape of a Delta, of course) but they were too good to last, my sisters found them and devoured them in 30 seconds flat.