Yes you could raise some crappie in a 5 acre lake. I have seen a friend's tank in here Texas with one acre and had crappie in the tank (pond). Just make sure to stock in some structure like trees or rocks and make sure they have a good supply of minnows or shad to eat. Minnows should suffice in the pond. Just make sure you get a good start of both bait fish and crappie to start you out. You can also talk to your local parks and wildlife officials I think and ask them where you could get the fish you need to start.