Did I read that right....60 pounds in 1 acre...and they are 1/2 pound fish?
I think that guy is trying to sell Tilapia. That's far more than you need...unless you are trying to feed Alabama. Based on my experience, 5 to 10 pounds per acre is plenty enough.
You will need to invite us all over to Ala. for a big fish fry at 60 pounds per...Hell, they might even mow your grass at that rate.