Add shrimp to a medium bowl, top with buttermilk and marinate at room temperature for at least 15 minutes.
To a separate medium bowl, add flour, paprika, garlic powder, onion powder, salt, black pepper, and cayenne pepper. Mix to combine. Set aside.
Working one at a time, remove the shrimp from the marinade, and dredge into the seasoned flour mixture, pressing lightly to coat. Repeat with the remaining shrimp.
To a large pot over medium heat, add about 2 inches of vegetable oil and heat to 350°F.
Carefully transfer the shrimp into the hot oil, frying in batches to avoid overcrowding. Fry for 2-3 minutes, turning occasionally, until the shrimp are golden brown and crispy.
Carefully remove the shrimp from the hot oil and place them on a paper towel-lined plate to absorb any excess oil.
Serve immediately with a squeeze of lemon and tartar sauce for dipping.