Rinse the Freshwater Fish Heads and Bones (Perch, Pike, Zander) well and put them into a large stockpot with cold Water.
Bring the pot to a gentle simmer over medium heat — do not boil hard — and skim any foam that rises to the surface for a clear broth.
Add a halved Onion, roughly chopped Carrot, sliced Parsley Root, a handful of Black Peppercorns, Bay Leaves and 1–1½ teaspoons of Salt. Reduce heat and simmer gently for 25–30 minutes to extract flavor from the bones.
Strain the broth through a fine sieve into a clean pot, discarding solids and reserving the clear stock. Taste and adjust seasoning if needed.
Add diced Potatoes to the strained stock and simmer until they are nearly tender, about 10–12 minutes depending on size.
Cut the Freshwater Fish Fillet into bite-size pieces and add them to the simmering soup; cook gently 4–6 minutes until the fish is just cooked through and flakes easily.
Stir in chopped Fresh Dill and Fresh Parsley a minute before serving so they stay bright and fragrant. Finish with freshly ground Black Pepper and more Salt to taste.
Ladle the ukha into warm bowls and serve immediately, accompanied by rye bread or lemon wedges if desired.
