Pat the fish fillets completely dry with paper towels and season lightly with salt and pepper.
In a shallow dish, whisk together the eggs and buttermilk, and in another shallow dish, combine the flour, cornmeal, paprika, garlic powder, onion powder, salt, black pepper, and cayenne pepper.
Heat 2 inches oil in a heavy pot to 350°F; keep pot less than half full.
Dip each fish fillet first in the egg mixture, then in the flour-cornmeal mixture, then back in the egg, and finally back in the flour-cornmeal mixture for a double coating.
Fry in batches 4–5 minutes per side until golden and fish reaches 145°F.
Remove the fish to a paper towel-lined plate to drain, and serve immediately with lemon wedges and sides.