Boil and dry the rice. Divide the fish into small flakes. Cut the whites of the eggs into slices and sieve the yolks. Melt the butter in a saucepan, add to it the fish, rice, egg whites, salt, pepper and cayenne and stir until hot. Turn the mixture on to a hot dish. Press into the shape of a pyramid with a fork, decorate with egg yolk and serve as hot as possible.