Thaw fish, if frozen. Cut one lemon half into slices or wedges; set aside. Juice the remaining lemon half. In a large bowl combine the lemon juice, mayonnaise, and honey. Remove 2 tablespoons mayonnaise mixture and set aside. For slaw, stir celery, apple, and cabbage into the mayonnaise mixture in bowl; set aside.
Rinse fish; pat dry with paper towels. Sprinkle fish with salt; brush with reserved mayonnaise mixture. In a shallow dish combine cornmeal and chili powder; coat fish with mixture.
In a 12-inch skillet heat oil over medium heat. Add fish to skillet; cook for 6 to 8 minutes or until golden and fish flakes when tested with a fork, turning once. Serve fish with slaw and the lemon slices or wedges.