Cut the fish into medium size and wash it carefully. Marinate with 1/2 tsp turmeric and a pinch of salt.
Prepare the masala: In a saucepan, dry fry cinnamon, cloves, cardamom, black pepper corns &, coriander powder, red chili powder, 1/2 tsp turmeric powder & bay leaf for around 3-4 mins in low heat. Add shredded coconut and stir well for another 2-3 mins. Take this off from the heat and wait to cool. Blend this masala to make a fine paste. Add little bit of water if required.
In an another deep saucepan, heat oil. Add sliced onion & garlic and sauté till lightly browned. Add green chilies, ginger julienne and tomato and saute for another 2-3 mins. Add blended masala and cook this for 4-5 mins in low heat. Stir occasionally. Transfer this masala into a small bowl and keep this aside.
In the same saucepan, add tamarind pulp and carefully place the fish pieces. Add water and cook this for 5-10 mins in medium heat. Transfer the prepared masala into this and stir slowly. Cook it for another 2-3 mins.
Season your dish with coriander leaves or curry leaves. Serve hot with Veg Pulav or Steamed Rice.