Heat 2 tablespoon butter in a pan and steam the shallots in it until translucent. Pour in the wine, simmer for 1 minute, then add the vegetable stock, orange-cream-horseradish and cream, season with salt and pepper and simmer for 5 minutes. Add 2 teaspoons of orange juice, mix with a hand blender until foamy and season if necessary.
Season the pikeperch fillets with salt, pepper and 3 teaspoons of orange juice. Heat the remaining butter in a pan and fry the fillet on the skin side for 2 - 3 minutes, then turn and fry for another 3 - 4 minutes.