Preheat the oven to 375 degrees F.Add the tomato sauce to the bottom of a baking dish.
Rinse the fish fillets and pat dry.
Sprinkle salt, pepper and fish seasoning (if using) to taste on both sides of the fish, and lay the fillets in the baking dish.
On a cutting board, chop the basil and mince the scallions.
Add the breadcrumbs to the pile of fresh herbs and chop roughly.
Top the fish fillets with the herb and breadcrumb mixture, then add the fresh tomato slices on top.
Bake in the oven for about 20 minutes (or until the fish is cooked through