This section is from the book "Meals Medicinal", by W. T. Fernie. Also available from Amazon: Meals Medicinal: With "Herbal Simples" Curative Foods From the Cook in Place of Drugs From the Chemist.
In common with the Sturgeon's Roe, as Caviare, already considered, other fish Roes comprise thirty per cent of proteids, and nineteen per cent of fats, also about four per cent of mineral matters. These proteids include a good deal of nuclein, which is a fertile source of uric acid, and therefore improper for gouty persons. The milt is the organ in male fish which corresponds to the Roe in females. Cod's Roe, fresh from the fishmonger, should be put for cooking into boiling water, first pricking the outside skin with a needle; then boil it for an hour, or more, and let it become cold; cut it in slices, and fry with a little butter, not in fat, or lard. Small pieces of bacon may be eaten with this cooked Roe, which is a suitable dish for the consumptive, or diabetic patient. With respect to herrings, the fish technically known as "Matties " are immature, before the milt, and the roe, have become developed. They are considered a great delicacy in Russia, and Germany. Botargo is a relish made of the roes of certain fishes, strongly salted after they have become putrid; it is much used on the Mediterranean coast, as an incentive to thirst. The best botargo comes from Tunis, being dry, and reddish in colour; this is eaten with olive oil, and lemon juice.
Pepys tells in his Diary how "we staid talking, and singing, and drinking great draughts of claret, and eating botargo, and bread and butter, till twelve at night, it being moonshine," The roe of the grey mullet is costly, having a faint honey-like scent, because of the beeswax used in preserving it.