You'll probably want to grow out a group of about 10 juveniles and pick the biggest/best coloured ones to breed from. I'd say you would want something around 4'x18"x18" for a breeding tank, and have a spare tank set up in case you need to separate them as males can be pretty hard on females around breeding time, especially in a smaller tank where she doesn't have space to get out of his territory.
Just a little side-track on the topic of breeding, make sure you carefully select the fish you are going to breed, not just that they are healthy and free of defects, but look at their colour, size, etc. In nature Darwin weeds out the weak and inferior and we need to make sure we do the same when breeding in captivity.