Sauté onions, bell pepper, celery, fennel seed and garlic in about 3 Tb of olive oil and 2 Tb butter until onion begins to turn translucent. Add 1 Tb creole seasoning. Add shrimp and crawfish and cook until shrimp are just done then remove from heat. Crush butter crackers by hand and stir into sauté. Mix in 1 tsp lemon zest, juice of 1/2 lemon, Parmesan cheese and chives and combine well. Taste stuffing and add more creole seasoning to taste. Brush fish inside and out with olive oil and lightly season with creole seasoning. Stuff fish and take care not to pack filling too tightly and wrap the top flaps around. Bake at 350 for 20 minutes or until stuffing is golden brown and flounder is done. Enjoy!