Here's an idea for a quick fish dinner—cod in tomato sauce with zucchini and kale—that you can have on the table in 20 to 30 minutes, depending on your proficiency in the kitchen.
First, heat a little fat in a sauté pan. (I use butter when cooking fish; I've read that the two complement each other nutritionally.)
Add a little garlic and/or onion to the fat, making sure they don't burn. When those are soft, add a little bit of strained, crushed or diced tomatoes. When those are warm, add some chopped zucchini and kale (or any vegetable you like) and cook the vegetables for about five minutes over medium heat. Also, add some salt, pepper and lemon juice when you start cooking the veggies.
Mix the sauce and add a couple pieces of cod filets (or other fish). Cook until the fish is 85 percent done, flipping the fish occasionally if you aren’t using a lid for the pan. If you are, you won't need to flip, since the part of the fish outside of the tomatoes will cook via steaming. Just make sure that the temperature in the pan doesn't get too high, which may cause the sugars in the tomatoes to burn.
Don't be skittish about cooking the fish to 85 percent; carryover cooking will handle the rest. Taste the sauce and reseason accordingly. Serve over brown rice, quinoa, whole wheat pasta, polenta, mashed potatoes, etc.