Perch, with Parsley Water, Celery Root and Parsnips

Scrape four ounces of parsley roots, and the same quantity of parsnips and the same of celery roots; cut them up into very fine shreds. Cook these separately in salted water for twenty minutes, then drain off the water. Cook the perch in this water, and when done and dressed, surround with boiled potato balls made three-quarters of an inch in size and the roots. Serve a part of the well reduced liquid in a separate sauce-boat at the same time as the fish.