Marinate fish fillet pieces for at least 30 minutes in 1 tsp turmeric powder, 1 tsp salt, onion powder, garlic powder, black pepper, curry powder.
Heat oil in wok and fry mustard seeds, curry leaves and red chilies.
Add onion, minced garlic, ginger and fry for a few minutes.
Add 1 tsp turmeric, 1 tsp salt, fish masala, and tomato ketchup and continue frying for a few minutes.
Add tamarind, lime juice, coconut milk, half and half and some water if necessary. Cook for 5 minutes.
Add the fish and pineapple and mix into the sauce. Add water if necessary.
Bring to a boil and let it simmer over low heat for 10 minutes.
Taste and check that the fish is cooked.