Gut the pike perch. Remove gills from the head. Cut off the head, tail and fins. Cut the fish along the chine bone and divide into 2 fillets, removing all the bones. Cover the fish head, chine bone, fins and tail with cold water, cook under a medium heat and bring to the boil, skimming off the foam. Peel onions, carrots, celery roots and parsley and cut into large pieces. Cut the fish into wide slices. Put the vegetables, bay leaf, pepper and a pinch of salt in the pan. Cook under a medium heat for 20 minutes. Strain the consommé into a clean pan. Pour in wine, bring to the boil, put the pieces of pike perch and simmer for 10 minutes. Carefully place the fish on a dish with a slotted spoon. Strain the consommé through a sieve covered with 4 layers of gauze. Soak gelatin in 0.5 cup of consommé and set aside for 20 minutes. When gelatin swells, add it to the pan with consommé. Warm up under a low heat, stirring all the time until gelatin dissolves. Remove from fire. Let the consommé cool a little, pour on a serving dish with a thin layer and refrigerate for 20 minutes. Then put half-rings of lemon, slices of fish, olives, halves of eggs and sprigs of dill on a half-frozen jelly. Top up the fish with a thin layer of consommé with gelatin. Refrigerate until complete gelation.