Heat the olive oil in a large pot over medium heat.
Add the diced onion, carrots, and celery to the pot and sauté until the onions are translucent and the vegetables begin to soften.
Stir in the minced garlic and dried oregano, cooking for 1 minute until highly aromatic.
Pour in the crushed tomatoes and vegetable broth, stirring to combine all the flavors.
Bring the liquid to a gentle boil, then add the diced zucchini and season with sea salt and black pepper.
Reduce the heat to low, place the cod pieces into the broth, and cover the pot.
Simmer for 5 to 7 minutes until the fish is opaque and flakes easily with a fork.
Ladle the stew into bowls and garnish with freshly chopped parsley.