My favorite pan for deep frying on the stovetop is a 6-quart stainless steel pot. It needs to be deep enough for the food to be submerged completely, with plenty of room above the bubbling hot oil. Many people recommend using a cast iron pot for deep frying. I tried it and found that the oil quickly rose above 350 degrees F, and the fish was coming out too dark. If you use cast iron, monitor the temperature closely before starting, and lower the heat a bit if needed. Don't use a nonstick pan, because of the chemicals that may be released during deep frying.