Season the fillets of pickerel with lemon pepper seasoning, pressing the spices into the flesh to adhere.
Spray the griddle pan with non-stick cooking spray and place over top the open fire, using a Muskoka grill to secure the pan. Place the pickerel fillets, skin side down, into the griddle pan. Cook until skin is crisp, about 3 to 5 minutes per side until fish is fully cooked and flakes easily with a fork.
Serve griddled pickerel on a plank with a wedge of lemon.