Rub the chambo fish with salt and let it marinate for about 15 minutes.
Heat the vegetable oil in a large skillet or saucepan over medium heat.
Add the chopped onion and sauté until translucent.
Stir in the minced garlic and grated ginger, and cook for another 2 minutes.
Add the diced tomatoes, bell pepper, and green chilies (if using) to the pan. Cook until the tomatoes start to break down and the bell pepper is tender.
Stir in the paprika, ground cumin, ground coriander, turmeric, salt, and black pepper.
Place the marinated chambo fish into the pan and pour in the fish or chicken stock.
Cover and simmer for about 20-25 minutes, or until the fish is cooked through and tender.
Garnish with fresh cilantro or parsley.
Enjoy your meal!