Slice the eggs in half lengthwise. Remove the yolks and put them in a bowl and then mash with a fork. Add in the mayonnaise, relish and mustard. Add salt and pepper to taste. Set aside.
Heat about 1-inch of vegetable oil in a skillet until a deep-frying thermometer reads 350 degrees F.
Combine the flour, cornstarch, baking powder and 1/2 teaspoon salt in a shallow dish and dip the fish in the batter.
Fry the fish until golden brown on both sides. Place on a paper-towel-lined plate to soak up any excess oil and season with salt. Let cool.
Add the catfish to the yolk mixture and break up with fork. Spoon some of the yolk mixture into each egg half and garnish with dill and paprika to serve.
Instead of making your own batter for the fish, you can also use a store-bought box of tempura batter prepared to the instructions on the box.