I agree with sugar and spice, it just seems risky to me for a rush party...i also echo the question of "wouldn't they smell after a while??" especially if, God forbid, any of them died during a party....imagine being with a PNM and talking about what a great idea having fish as a party decoration is, how entertaining they are, etc. and then having her say "Uh, is the floating thing a trick or something?"...and if you had a lot of them, you'd have to have fish monitors for all of the parties!
i think it would come off better if you just got one for the house and named it ralph or something and put it in a nice bowl...that way you can say that the sorority has a pet, it's being taken care of by sisters AND it's a pretty decoration
and just curious, is it just plant roots that are bad for fish? what if they were just cut roses or bamboo or something? or plastic fake ones even? i haven't had a fish since i was eight, but i'm thinking about getting one for my dorm room this year