Boil the potatoes and peel them. Fish clean the skin and bones. Spread with mayonnaise bottom of the salad bowl. Top Grate cooked and chilled potato in large pieces grater (can be salted potatoes, but carefully, the fish is quite savory), spread with mayonnaise. Put mayonnaise on cleaned and cut into small pieces of fish, again mazhem thin layer of mayonnaise. Grate the onion on top cheese grater and ready.