In medium bowl, combine flour, baking powder, seasoned salt, paprika, garlic powder and onion powder. Place half in a 1-gallon recloseable food storage bag; set aside.
Add beer or club soda to remaining ingredients in bowl. Whisk until well combined; set aside.
In large skillet with high sides, fill halfway with oil. Heat over medium-high heat until oil reaches 375°F or small amount of batter sizzles when placed in the hot oil.
Place fish fillets, in batches, into the flour mixture and shake to coat. Remove and dip into batter. Carefully place in oil and fry until golden brown and fish is cooked through, turning once (about 3-4 minutes). Remove from oil with a slotted spoon and drain on paper towels. Keep warm while frying remaining fillets. Serve fish with tartar sauce.