Rinse fish thoroughly in cold running water to remove all blood and viscera. Pat dry with paper towels. In small bowl, combine 1/2 teaspoon salt (if desired), 1/8 teaspoon pepper, celery seed, thyme, garlic and juice; mix well. Rub fish well with mixture, inside and out. Place in large rectangular baking dish. Cover and refrigerate 2 hours.
To make stuffing, in medium saucepan, melt 2 tablespoons butter over low heat. When hot, add onions, bell pepper and garlic. Saute vegetables several minutes until tender. Remove saucepan from heat; stir in bread crumbs, olives, peanuts, remaining salt and pepper. Heat oven to 400 degrees. Remove fish from refrigerator. Fill with stuffing mixture. Dot fish with remaining butter; bake 40 minutes or until fish flakes when tested with a fork. Remove from oven; transfer to serving platter. Garnish with watercress and lime.