I’m a propane cooker/cast-iron guy as well. For the pan, make sure to get one as deep as possible. I’ve got a 10″ Lodge Logic dutch oven and it works pretty well. As mentioned, the cast iron holds heat better and also prevents heat spikes as easily. Just a more even and consistent cook.
You don’t need all that depth on the pan for the fish, as much as you do for other things like fries, onion rings, etc. All that cold surface area on those smaller items can give you a boil-over too easily if you skimp on a short-sided pan.
Joel