Steam or bake the carp, then remove the meat from the bones. Reserve 2 cups. Prepare vegetables: slice onion in 1/4-inch-thick rings, then cut the rings in half; slice peppers lengthwise in 1/4" strips; and slice celery 1/2" thick. Melt the 1/4-cup butter in a large saucepan or skillet. Add flour and stir until light brown. Add onion, peppers and celery. Cook and stir until vegetables are softened. Add broth and seasonings.
Bring mixture to a boil, then simmer until vegetables are almost done and broth is slightly thickened, about 15 minutes. Add tomatoes, shrimp and carp. Cook until shrimp is done, about 5 minutes. Serve over rice and garnish with parsley. Serves 4.