This delicacy falls into two categories — hard roe and soft roe. Hard roe is female fish eggs, while soft roe (also called white roe) is the milt of male fish. The eggs of some crustaceans (such as lobster) are referred to as coral. Roe can range in size from 1 to 2 ounces to over 3 pounds. If the fish is small, the roe is cooked inside the whole fish. The roe of medium and large fish is usually removed and cooked separately. Most fish roe is edible but others (including that of the great barracuda and some members of the puffer and trunkfish families) are toxic. The choicest roe comes from carp, herring, mackerel and shad, but those from cod, flounder, haddock, lumpfish, mullet, perch, pike, salmon, sturgeon and whitefish also have their fans. Salting roe transforms it into caviar. Roe is marketed fresh, frozen and canned. Fresh roe is available in the spring. It should have a clean smell and look moist and firm. The extremely fragile membrane that holds the eggs or milt must be gently washed before preparation. Roe can be sautéed, poached or, providing it's medium-size or larger, broiled. It can also be used in sauces.