Peel, wash and coarsely dice the celery and potatoes, cover and cook in salted water for about 20 minutes.
Rinse chanterelles briefly, dab dry, clean and cut large chanterelles smaller. Cut bacon into fine strips. Peel and chop the shallots. Wash sage and dab dry. Rinse pike-perch fillets, dab dry and cut into 4 pieces.
Drain the potatoes and celery. Add milk and butter and mash everything to a fine puree. Season to taste with salt and nutmeg. Cover and keep warm in the pot.
Fry the bacon in a large pan without fat until crispy. Fry the shallots and sage briefly. Remove everything. Heat 2 tablespoons of clarified butter in hot bacon fat. Fry the chanterelles for 4-5 minutes while turning.
Add the bacon mixture again and season the mushrooms with salt and pepper.
Meanwhile salt the fish and press it with the skin side into the flour. Shake off excess flour. Heat 1-2 tablespoons of clarified butter in a second pan. Fry the fish for about 3 minutes until crispy on the skin side.
Then turn and fry from the other side for 1-2 minutes. Serve everything.