Wash the fish well. Season with salt and pepper.
Shallow fry both the sides of the fish till done. Drain. Remove the thorns and smash the fish completely.
In the same oil (add more if required), splutter the mustard seeds. Add the ginger garlic paste and curry leaves and saute till raw smell is gone.
Add the shallots and green chillies. Saute till wilted.
Add the spice powders and saute for a minute.
Add in the smashed fish and coconut and give it a nice toss. Simmer for around 5 minutes. Adjust seasoning.
Serve warm as side for rice or along with chapathis.