Please tell me you're kidding.... lol. If you're not, I sure hope you have another bathroom, or you're sure gonna start stinkin in a few days w/out a shower.
Hmm, well the bath tub is not actually that big, the average tub only holds about 60 gallons of water which is half the recomended size for keeping stingrays, nice idea but back to the drawing board i think, looks like youll have to start saving for a 120 gallon tank.