What are the criteria for Fry, Juvie, Young Adult, Breeder, Show Fish description of the age and size of Swordtails?

It really depends more on the your perspective which is usually based visually on size rather than age. Approximately any swordtails less than ¾ “ would be perceived as fry and any larger than that would be considered Juvies, once they are mature enough to begin or start dropping fry Young Adult Size and Larger Fish would be considered Breeder Show Stock.