Portuguese Seafood Stew that Reminds Us of Portugal

Name: Portuguese Seafood Stew that Reminds Us of Portugal
Ingredients: 1/2 pound medium-large shrimp, peeled and deveined, shells reserved; 2 teaspoons olive oil, plus more to serve; 1 large, sweet onion, halved pole to pole and sliced; 1 large bulb fennel, sliced thin, fronds reserved; Kosher salt; Fresh ground black pepper; 3 large carrots, diced; 3 large cloves garlic, sliced thin; 4 Yukon gold potatoes, cut into approximately 1-inch pieces; 4 plum tomatoes, peeled, seeded, and chopped (use canned in the winter and spring); 2 cups white wine (that you like to drink); 2 pounds fresh white fish filets (I usually use two types of fish—whatever is freshest); Juice and zest of 1/2 lemon, preferably Meyer; Red pepper flakes or Aleppo pepper as desired (plus more if desired); 1 teaspoon fennel seed, crushed with mortar and pestle or ground in spice grinder (or more to taste); 1 to 2 tablespoons chopped Kalamata olives (optional)