Thaw fish, if frozen. Rinse fish. Cut into 3/4-inch pieces. Set aside.
In a medium saucepan combine chicken or vegetable broth, shredded carrot, chopped celery, and sweet pepper. Bring mixture to boiling; reduce heat. Cover and simmer for 2 minutes. Stir in corn and evaporated milk. Bring mixture to boiling, stirring occasionally.
Add fish; reduce heat. Cover and simmer gently for 3 to 5 minutes or until fish flakes easily with a fork. Gradually add cheese, stirring until melted. Garnish with celery leaves, if desired. Makes 4 servings.