The Scorfano fish(rock cod) is my wifes favorite fish, when my nephews catch them it is the only fish I have to pay for as the restaurants on Hvar pay big money for the fish. This is because the Italian Tourists will pay $60 to $80 for a fish for two people in a relatives restaurant in the harbour.
My wife cooks only the whole gutted fish like this.
Sweat onion slices and potato chunks in olive oil, add good white wine and boil off the alcohol, add fish stock and simmer till the pots are nearly done.
Then sit the scorfano on the pots out of the liquid and cover the pan so the steam cooks the fish.
Take the fish out and place on a warm plate, season the broth (the pots should retain their shape) and serve in separate bowls.
Google Croatian Brodetto, this mixed fish stew is called locally Rich mans Brodetto if one of the fish is what you call rock cod