Fish steaks, cut 1 1/2 to 2 inches thick—halibut, swordfish, and tuna are all good choices—are really best for grilling. Fillets are usually too delicate, and large whole fish are tricky—too often the outside is charred before the inside is cooked. If you're lucky enough, however, to find small whole fish, such as sardines, imported red mullet, small mackerel, or bluefish, they will be exquisite cooked over charcoal or the embers of a wood fire for a real Mediterranean-style treat.
Count on 1/4 pound boneless fish steaks per serving, a little more with the bone in, and add a little extra for enthusiastic appetites.