In a large bowl, whisk together milk and hot sauce. Add catfish, tossing to coat. Cover and refrigerate for at least 1 hour.
In a large Dutch oven, pour oil to a depth of 4 inches, and heat over medium heat until a deep-fry thermometer registers 340°.
In a large shallow dish, whisk together cornmeal, salt, pepper, garlic powder, and onion powder.
Remove catfish from bowl, discarding milk mixture. Dredge catfish in cornmeal mixture, shaking off excess.
Working in batches, fry catfish until golden brown, 3 to 4 minutes. Let drain on paper towels. Serve with lemon wedges and tartar sauce. Garnish with parsley, if desired.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/cornmeal-fried-catfish/