Filet and clean a 3 lb trout, saving the bones. Place bones in a boiler with 1 quart of water, juice of 1 lemon, 1 onion cut in quarters, 1 stalk of celery, 1 carrot, 1 bay leaf, and 3-4 whole cloves. When it boils, skim surface and let simmer until it is reduced one-third.
Blend 2 Tbsp butter with 2 Tbsp flour and let cook for 5 minutes without browning. Stir in strained fish stock and let simmer for 10 minutes, stirring continually. Remove from fire and strain.
Add salt and pepper to taste. Stir in 1 4-oz can of mushrooms, 12 boiled shrimps and 12 medium oysters that have been poached and drained. Stir in one small glass of sherry wine.
Cut trout in individual servings, place in bake dish with 1 onion, 1 bay leaf, 2 Tbsp vinegar, and 1 Tbsp salt. Cover with cold water and let poach or simmer until fish is done but still firm.
Transfer fish to hot serving platter, and pour sauce over fish. Sprinkle lightly with paprika and put under broiler flame a minute to glaze. Serve garnished with lemon slices, parsley sprigs, and small buttered boiled potatoes.