Preheat your oil for deepfrying. Cut your haddock fillets in half ,and check for bones around the edges.Sprinkle with some pepper.You want nice size pieces of fish, but not too overly big.
In a bowl,mix together your flour,baking powder,salt and cold water.Whisk together until u have a smooth paste,not too thick and not too runny.You may need to add a little extra water if needed.
Dip your fish into the batter with a fork,coat all sides well and let the extra batter drip off some.Put into your heated oil and hold the fish ontop for a few minutes before u let it go into the oil ( this will help the fish from not sticking to the sides or the other pieces of fish)
Only cook a few pieces at a time.Do not overcrowd.Let cook a few mins.,when the fish floats on the top and is golden brown,flip it over on the other side and cook a few mins. more.Approx. 3 mins. per side.With a slatted spatula, lift your fish out of the oil and let the oil run off.
Put your cooked pieces of fish onto some papertowel or parchment paper , on a cookie sheet, and keep warm in the oven until all your fish has been cooked.Serve with some french fries or your favorite side dish.