In a wide, shallow skillet, heat the olive oil over medium heat. Add the chopped onion and cook until soft and golden, about 6 to 8 minutes. Stir in the bell peppers and garlic and cook for another minute.
Add the salt, black pepper, and paprika, stirring well to coat the vegetables. Stir in the tomatoes and cook for 3 minutes, letting them soften and break down slightly.
Add the rice and saffron liquid, stirring to coat the grains evenly. Pour in the stock and bring to a gentle simmer. Cook over medium heat for 12 minutes, stirring occasionally, until most of the liquid is absorbed.
Arrange the seabass strips over the rice and place the whole chili peppers in the center. Cover loosely with foil and cook for 3 to 4 minutes more, until the fish is opaque and flakes easily.
Scatter with chopped parsley and finish with a squeeze of lemon just before serving.