Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   6      tablespoons   butter or margarine
   1      cup           onion -- chopped
     1/2  cup           celery -- chopped
     1/2  cup           green pepper -- chopped
   6      tablespoons   flour -- all-purpose
   1 1/2  cups          milk
   1 1/2  teaspoons     salt
   1      teaspoon      pepper
     1/4  teaspoon      thyme
   1      dash          hot sauce
   1      pound         fish fillets; thawed
   1      cup           breadcrumbs
     1/2  cup           cheese, cheddar; shredded

Preparation:

Melt butter over low heat in a saucepan; sauté onion, celery, and green pepper until tender. Blend in flour, stirring well. Gradually add milk, stirring constantly. Cook over medium heat, stirring constantly, until smooth and thickened. Add salt, pepper, thyme and hot sauce, blend well. Place fish fillets in a buttered 8" square baking dish; cover with sauce. Combine breadcrumbs and cheese; sprinkle over sauce. Bake at 450F for 20 to 25 minutes or until fish is done.