- Cut the fish fillets into burger-sized pieces. 
- In a shallow bowl, mix the flour, garlic powder, paprika, salt, and black pepper. 
- In another bowl, pour the buttermilk. 
- In a third bowl, place the breadcrumbs. 
- Dip each piece of fish first into the flour mixture, then into the buttermilk, and finally coat it with breadcrumbs. 
- In a large skillet, heat about 1 inch of vegetable oil over medium-high heat. 
- Once the oil is hot, carefully add the breaded fish pieces in batches, frying for about 3-4 minutes on each side or until golden brown and cooked through. 
- Remove and drain on paper towels. 
- Toast the hamburger buns lightly. 
- Assemble the burgers by placing a piece of fried fish on the bottom half of each bun, adding lettuce, tomato slices, and a generous dollop of tartar sauce. 
- Top with the other half of the bun. 
- Serve immediately while hot and crispy.