Marinate the Karimeen in half-teaspoon turmeric and salt for ten minutes.Then semi fry it in coconut oil.
In 30 ml coconut oil sauté sliced onions, ginger, garlic and curry leaves till onions are golden brown. Then add tomatoes and the turmeric and stir well. Add turmeric, chilly powder, coriander, salt and coccum. Add the 2nd milk of coconut. Place fish and boil for five minutes. Add first coconut milk, simmer and take off fire.
On a separate skillet, add oil and temper mustard seeds,curry leaves and shallots. Garnish the fish with this and serve hot.