Nice! I know someone who got their Dats to 12" in a year. He has a pretty big tank and crazy filtration. How big of a tank do you have and what are you feeding them?
I have them in a 120 long (the old perfecto 5 footer), and I feed them bloodworms, blackworms, nightcrawlers, frozen crappie minnows, and live crappie minnows (that i keep in a tank in the basement) that have been fed with high nutrition fish food.