I have never brought it up to a new girl unless asked somthing along the lines of "do you have any pets?" but I do always make sure before I bring them to my place that all tanks are 110% tip top condition and I usually get a good response for my efforts. I agree with Jkessler623 though, she dosent have to be interested in or even like my hobby, but if she is negative twards my daily dose of relaxation and sanity then it probably wont last very long.