You can cook as many fish as you want - this preparation was done in a convection oven with three small fish. For three fish I used two medium sized fennel bulbs. About half of one bulb was chopped and sauteed lightly in a pan with olive oil and garlic, with a splash of white wine at the end (I usually cook with an Orvieto). This mixture was then spooned into the cavity of the fish along with a sprig of fresh rosemary. The rest of the fennel was sliced and put in the bottom of a glass baking dish, on parchment paper, with some more chopped garlic. The stuffed fish were placed on top, then the whole dish was given a liberal dose of olive oil, salt, and pepper and put into a very hot over - in the U.S. I would say around 400 degrees. It is done when it is done - you never want to overcook fish, but you do want it to get crispy on the edges, and for some of the fennel to brown. To serve, place a fish on a plate, and spoon over the fennel with the juices left over. If you pan dries out while cooking, add a little more white wine. You can dress it at the end with a little fresh olive oil and some salt.