Add rice to the boiling broth and cook for 20 minutes. Wash the fish, sprinkle with 4 tablespoons of lemon juice and salt. Boil up salted water in a large shallow pot and let the fish simmer for 10 minutes.
Drain the fish and cut into bite-sized pieces. Mix mayonnaise and milk and season to taste with curry, salt and pepper and remaining lemon juice. Mix the rice with the mayonnaise. Fold in fish, crabs, peas, raisins and cashew nuts and leave to stand for 1 hour.
Season again with salt, pepper and curry.