1 (12-ounce) can evaporated milk
1 teaspoon crab boil seasoning (recommended: Old Bay)
1/2 teaspoon freshly ground black pepper
1 1/2 teaspoons kosher salt
1/2 onion, thinly sliced
3 to 4 catfish fillets
Combine the milk, crab boil seasoning, pepper, salt, and onion in an electric skillet, cover, and bring to a simmer. Add the catfish to the liquid, spooning some of the liquid over the fillets.
Reduce the heat to low, around 140 to 145 degrees, cover the skillet, and poach for 6 to 9 minutes.