Toss the Tilapia (seasoned with salt and pepper), tomatoes and mushrooms together. 

Place in a clear baking dish (to see doneness of fish) covering the bottom. 

Spread the mashed potatoes on top of the mixture and bake at 350 degrees for 30 minutes or until the fish is cooked and the potatoes are browned.

Serve with Garlic Bread and Salad.