For the catfish: Whisk together the buttermilk, 1 tablespoon of the seafood seasoning, 1 teaspoon of the chipotle and 1/2 teaspoon each salt and pepper in a medium bowl. Add the fish, cover and let soak, refrigerated, for 10 to 15 minutes.
For the fiesta slaw: While the fish is soaking, whisk together the mayonnaise, crema, lime juice, paprika, salt, pepper and hot sauce. Add the cabbages, cilantro, carrots and green onions and toss to coat.
Whisk together the cornmeal, flour and remaining 1 tablespoon seafood seasoning and 1 teaspoon chipotle in a shallow dish or paper bag. Drain the catfish, shaking off any remaining marinade (discard the remaining marinade). Place 3 to 4 pieces of fish in the cornmeal mixture and shake/flip until they are coated. Remove the fish to a clean plate or baking sheet. Repeat with the remaining fish.
Add about 1 inch of canola oil to a large cast-iron skillet over medium-high heat and heat to about 375 degrees F.
Add the fish to the skillet a few pieces at a time. Fry on each side until golden brown all over, 2 to 3 minutes. Remove to a baking sheet with a cooling rack. Repeat with the remaining fish.
Toast the tortillas in a cast-iron skillet or over an open flame. Add 2 pieces of fish to each tortilla and top with the fiesta slaw. Serve with lime wedges, cilantro and red onions.