Remove the scales and fins of the fish. Remove visceral parts. Wash the fishes with salt and water thoroughly. Cut them into round pieces. Apply turmeric powder, some salt and one spoon red chilly powder to the fish pieces. Keep them aside.
Prepare spicy paste by grinding all the ingredients for spicy paste.
Peel the mangoes and cut into thin slices.
Add oil to a deep bottomed pan and heat. Fry the onion pieces till dark brown. Add slightly mashed garlic bulbs, lengthwise split green chillies and the spicy paste. Fry till the raw smell of spicy paste is gone.
Add the mango slices and remaining one spoon of red chilly powder and cook until the mango slices become smooth.
Add the fish pieces and turn all the contents up and down gently and carefully so that the fish pieces do not get damaged.