Heat the olive oil in a large pot over medium heat. Add the onion and cook until it softens, about 5 minutes.
Stir in the garlic and cook for 1 minute until fragrant.
Pour in the white wine and let it simmer for 3 minutes to reduce slightly.
Add the crushed tomatoes and fish stock. Season with salt and black pepper. Bring the mixture to a gentle boil, then lower the heat and simmer for 10 minutes.
Add the white fish chunks and cook for 3 minutes.
Add the shrimp and mussels. Cover the pot and cook for 5 minutes until the shrimp turn pink and the mussels open.
Remove the pot from the heat. Stir in the chopped basil.