In A Saucepan, Saute Green Pepper In Butter Until Tender. Stir In The Flour, Sugar, Salt And Pepper Until Blended. Gradually Add Milk, Stirring Constantly. Stir In Tomatoes. Bring To A Boil; Cook And Stir For 2 Minutes. Add Tuna And Creole Seasoning; Heat Through. Serve Over Rice If Desired.