The oil temperature has the biggest influence on the outcome of your catfish. If you add your fish to the oil before it has had time to come to temperature, then the breading on your fish will absorb all the oil.
To get that golden nice and crispy fish, it is imperative that your oil is at the correct temperature. Using a cooking thermometer is the best way to ensure the correct temperature. Also make sure that your catfish has reached an internal temperature of 145 degrees F before consuming.