Sprinkle fish generously with salt and pepper.
Arrange half of lemon slices in bottom of shallow baking dish; add fish in single layer.
Place remaining lemon slices atop and around sides.
Combine butter and garlic; pour over fish (and baste with it later).
Add hickory to slow coals.
Place baking dish on heavy-duty foil atop grill.
Close smoker hood; cook slowly, about 1 hour, turning once.
Serve with the cooked lemon slices and butter mixture.