Pat the catfish fillets completely dry with a paper towel to ensure a crispy crust.
In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, cayenne, oregano, thyme, sea salt, and black pepper.
Generously coat both sides of the catfish fillets with the spice mixture, pressing it firmly into the flesh.
Heat the avocado oil in a large cast-iron skillet over medium-high heat until it is shimmering and very hot.
Place the fillets in the skillet and sear for 3 to 4 minutes per side until the crust is blackened and the fish flakes easily with a fork.
Remove the fish from the pan and set aside on a plate to rest.
Add the sliced bell peppers and black beans to the same skillet, using the remaining oil and spices to season them.
Sauté the vegetables for 3 to 5 minutes until tender-crisp, then serve immediately alongside the blackened catfish.