Celery is peeled, cut into thin slices and boiled until tender in salted water to which is added lemon juice. Allow to drain well. Cut into rings onion and garlic fry in the butter, until they become transparent. Pour the cream mixture and stew 5 minutes, then season with salt and pepper to taste. Grate horseradish finely grater, mix with celery and cream sauce and everything was ground to a smooth puree. The fish is cleaned of skin and bones and cut into slices, which are arranged on a plate for serving. Is well distributed around the cooled vegetable mousse. Appetizer can decorate with lemon slices and sprigs herbs.