In a small bowl beat eggs, milk and salt with fork.
Heat butter in a medium frying pan. Pour in beaten eggs. Reduce heat slightly until omelet is half set, lifting the edges. While the top of the omelet is still liquid, spread the whitebait over it. Continue to cook until the egg is almost set. Season with salt. Remove the pan from the heat and leave the omelet to stand for about 2 minutes.
Roll up the omelet, and place join downwards on the plate. Cut into 4 diagonal slices. Serve hot.