Put the saffron threads in a large, wide, heavy-based pan over a moderate heat and stir constantly until they just begin to give off their aroma. Pour in the fish stock and bring to the boil. Remove the pan from the heat, cover and set aside to infuse.
To prepare the squid, pull the head, tentacles and insides from the bodies. Discard the head and the hard beak from the base of the tentacles. Pull out the clear quill from the bodies, and discard. Use your fingers to rub the thin grey skin from the bodies, holding them under running water. Slice the bodies into thin strips and chop the tentacles. Set aside.
Heat 1 tablespoon of the oil in a frying pan. Add the monkfish pieces and quickly fry on all sides until lightly browned. Remove the fish and set aside. Add the remaining oil to the pan. Add the garlic and onion and cook over a moderate heat for 2 minutes, stirring occasionally. Stir in the fennel and continue cooking until the vegetables are softened but not brown, about 3 minutes.
Stir in the arborio rice so all the grains are well coated with oil. Stir in the white wine, and cook until all the wine is absorbed.
Stir in the saffron-infused stock, a ladleful at a time, cooking and stirring the rice constantly until each addition of the stock is absorbed. When about 3/4 of the stock has been added, stir in the browned monkfish and squid. Season with salt and pepper to taste.
Sprinkle with the fresh dill or parsley. Remove the pan from the heat, cover and leave to stand for 2 minutes before serving.
It's easy to make your own fish stock. Just simmer the head, skin and bones from any white fish. You can include the shells of prawns for a richer flavour.