Read the label on the sack of fish. There will be directions for how to bake, fry, etc it. Wherever it says butter use olive oil. If you use breadcrumbs make your own or check for soy. Repeat on the vegetables.
Be sure to read the label on your instant potatoes to be sure they're non-dairy non-soy in the box. When making them use rice milk and olive oil instead of whole milk and butter.