In a large pot, heat olive oil over medium heat. Add diced onion, minced garlic, chopped green bell pepper, and sliced celery. Sauté for about 5 minutes until softened.

Stir in Cajun seasoning, smoked paprika, salt, and black pepper. Add diced tomatoes and fish or vegetable broth. Bring to a gentle simmer for 5 minutes.

Gently add chopped white fish fillets to the soup. Cook for 5 to 7 minutes, stirring occasionally, until the fish is opaque and flakes easily.

Ladle the soup into bowls, serve over cooked rice or quinoa if desired, and garnish with freshly chopped parsley or green onions.