Step 1 - Gather Ingredients
1-1/2 lb. ocean perch, cod or whitefish fillets, 1 inch thick
1/3 cup butter or margarine , divided
1/2 cup chopped celery
1/4 cup chopped onion
1/4 cup chopped green pepper
1 Tbs flour
1 cup chopped tomato
1/2 lb. (8 oz.) Velveeta Pasteurized Prepared Cheese Product , cut up