I'm sure I depends on the part of the country you live in, Southern states with warmer water will
have faster growth rates.
It depends on the lake, as well as the region. There is a lot of nutrient rich lakes that will churn out fast crappie growth. As I recall, a 7 or 8 year old crappie has lived a full life, and in a good lake in our region they will be huge. If I had to guess, Sirjet, A six inch crappie will probably be around a year old.