Fish Biryani

Ingredients:
•1(.36) kg Fish 1.36 kg
•750 Grams Yogurt 
•2 Packets Bombay biryani masala 
•2 tbsp ginger garlic paste
•2 tbsp salt 
•2 kg Rice 
•4 tbsp Oil for Marination 
• 2 tsp Chilli powder ( for marination)
•4 Tbsp Cornstarch 
•oil to fry fish