I would like to have a breeding pair. I tried to purchase a male and female from a LFS but ended up with two males. Yesterday I spent fifteen minutes watching a tank but couldnt tell which were the females. Would it be alright to purchase a bunch and put them in a 50 gal tank until they pair off? Once they do, I would donate them back to a LFS or give to my neighbor. If this is ok, how many should I buy?