FISH BIRYANI

Ingredients :
450 grams rohu (any white fish fillets)
1/2 cup vegetable oil
1 level teaspoon cumin seeds, 1 clove
4 garlic cloves, chopped
1 inch piece ginger fresh, peeled
1 teaspoon ajwain seeds (carom)
4 green chillies
1/2 teaspoon red chili powder
As per taste salt