Fat Tails are pretty easy to breed. You can get a pretty high sucess rate when it comes to hatching, and if you're incubating for gender, its nearly a guarantee you'll get the sexes you want. In case you don't know, 82-84 for females, 85-86 for a mix, and 87-88 for males. One degree higher or lower, and theres still a good chance of getting the genders you want.