In a deep skillet, cook onion and garlic in olive oil on medium heat for a few minutes until soft.
Add tomatoes, peppers and spices, stir and cook until tomatoes are soft, about 2-3 minutes.
Lay fish fillets in the sauce, cover and cook on medium-low until fish flakes easily, approx 12-15 minutes.
To serve, place fish on plate and spoon sauce on top. Serve immediately.