Place fish in a deep pan, add 5 cups of water and bring to a boil. Reduce heat and simmer for 6-8 minutes. Drain and reserve the stock. Discard the skin and bones and flake the fish. Set aside. Put the potato, celery and onion in a pan with 3 cups of reserved stock. Bring to a boil and reduce heat and simmer until the vegetables are tender Set aside. Melt the butter in a large pan over low heat, add the bacon and fry until crisp, stir in flour, mustard and Worcestershire sauce and cook for 1 minute. Remove from heat and stir in milk, then return to heat and stir until thick. Add cooked wild rice, vegetables and stock mixture and fish. Simmer for 5 minutes then add cream and serve.