You can use Pomfret (avoli), fresh tuna (choora), Prawns, Mackerel (ayala) for this recipe. You can use dry chilli and coriander seeds, instead of chilli powder and coriander powder, while roasting the coconut. If you are using it, use around 5-6 dry chilli and 3/4 tbsp of coriander seeds. In that case, add the dry chilli and coriander seeds along with the coconut. Add tomato, only after checking the sourness of the gravy. If the curry already has required sourness/tangy taste from the cocum, do not add tomato. If you don't have cocum, you can use tamarind pulp instead.