Rinse the smelts thoroughly and pat dry. Place the bread crumbs, salt and pepper into a large resealable bag and shake to combine. Place the lemon juice into a shallow dish. Dip the smelts into the juice and then place in the bag with the dry mixture and shake until the fish are well coated. You can coat 2 to 3 fish at a time, depending on their size.
Place enough peanut oil into a 12-inch cast iron skillet just to cover the bottom of the pan. Place over medium-high heat until shimmering. Add the smelts to the pan, 4 to 5 at a time, being careful not to overcrowd the pan. Fry for 3 to 4 minutes per side until lightly browned and cooked through.