We don't have shad up here, that is why I think the typical lake shiner minnow up here is about 1" to 1-1/2" that or they are eating small bugs. I guess the main thing would be to match the size of the available forage that the fish are eating. And about the only way is to catch fish then cut the stomach open. I very rarely find anything very big in there stomachs. We are talking crappie. I have noticed before that on this crappie board there is a big difference in how people fish for crappie down south, and how we fish for them up here in the far north. You go small with light line no bigger than 4 Lb test, or get skunked.