Mediterranean fish soup is a delicious combination of fish and shellfish, vegetables, and a slightly fennel-tomato-Pernod fish stock. It does not take long to cook but there is a lot of prep work. You can find the recipe by Rick Stein, famous British chef, on the internet here.
A couple of caveats about the recipe is that it seems complex with all sorts of fish that you’ve never heard of and boiling bones for fish stock. We just use fish we know that will hold up in the soup like salmon and cod and whatever shellfish we have in the freezer, usually shrimp and scallops. John makes shrimp stock by using shrimp tails that we’ve collected and froze. We also use the juice from the tomatoes and a bottle of clam juice.
So you saute the veg and then add the fish stock and clam juice plus the tomato juice. The potatoes and tomatoes also go in at this point. After the potatoes are tender you add the fish for about two minutes and then the shellfish and turn off the heat. The shrimp and scallop pieces we used cook in just the hot soup liquid.
I went the extra yard and peeled and chopped up five Roma tomatoes but you could use a can of petite diced tomatoes. For the stock I think that a two bottles of clam juice and vegetable stock could work. The recipe calls for very precise vegetable slices but I made mine chunkier. We also added an extra pieces of orange rind because it is so delicious in the soup. John put in some saffron at the end but it is not called for in the recipe. I would definitely use shrimp, they are great in the soup, the scallops less so. We used a half pound each of salmon and cod.

Our Mediterranean fish soup was served with a drizzle of olive oil, a fennel frond, and some crusty bread
Although this sounds like an all-day project, you will have enough for at least another dinner. Making it on a weekend would probably work best and then you would have a dinner you just have to just heat up on a week-day evening.