What common preparation element makes commercially available catfish non-compliant on a carnivore diet?

Breading or battering.

The primary obstacle to incorporating catfish into a strict carnivore eating plan is the typical method of commercial or restaurant preparation. These methods frequently involve applying coatings like breading or battering, which inherently introduce plant-derived ingredients such as flour or cornmeal. Since the core requirement of the diet is the complete exclusion of grains and starches, any preparation method utilizing these binders renders the food item non-compliant, necessitating preparation methods that only use animal fats and salt.