Stuffed Gefilte fish

We cut one carp into slices two centimeters wide (we leave the head and tail intact).We cut off the head of the second carp and put it there. Sprinkle with one teaspoon of salt, two teaspoons of sugar and pepper. We send it to the refrigerator for 24 hours. The second carp is cleaned of bones, skin and ground with onions. Mix the minced meat with an egg, one tablespoon of sugar, a teaspoon of salt, pepper and breadcrumbs. The minced meat should be dense enough to make cutlets out of it. If it turned out to be liquid, then add more breadcrumbs. We keep the minced meat in the refrigerator for 24 hours too.
Pour three glasses of water into a saucepan, lower the cutlets there, fill the space between them with slices of fish. Bring to a boil. In boiling water, we throw carrots in circles, onions and all fish heads. Water should cover them. We cook all this over low heat for two hours.
Pour the contents of the pan onto a sheet with high walls, as for jelly. And we expose it to the cold until the liquid hardens.
Served cold with any sauce.