that garum is really the liquor from putrefaction." Garum was made in the Roman outposts of Spain almost exclusively from mackerel by salting the scrap fish innards, and then sun fermenting the flesh until it fell apart, usually for several months. The brown liquid would then be strained, bottled, and sold as a condiment. Remains of Roman fish salting facilities can still be seen, including in Algeciras in Spain and near Setúbal in Portugal. The process lasted until the 16th century when garum makers switched to anchovy and removed the innards. Garum was ubiquitous in Classical Roman cooking. Mixed with wine it was known as oenogarum, or with vinegar, oxygarum, or mixed with honey, meligarum. Garum was one of the trade specialties in Hispania Baetica. Garum was frequently maligned as smelling bad or rotten, being called, for example, "evil-smelling fish sauce" and is said to be similar to modern colatura di alici, a fish sauce used in Neapolitan cuisine. In English garum was formerly translated as fish pickle. The original Worcestershire sauce is a related product because it is fermented and contains anchovies. Difference from oyster sauce While fish sauce and oyster sauce are both briny and may have related histories, they are different products. Fish sauce is watery, clear, and salty, whereas oyster sauce is made by reducing oyster extracts and therefore sweeter with a hint of salt and not as strong an aroma as fish sauce. Ingredients and manufacture Fish sauces historically have been prepared from different species of fish and shellfish, and from using the whole fish, or by using just fish blood or viscera. Most modern fish sauces contain only fish and salt, usually made from anchovy, shrimp, mackerel, or other strong-flavored, high oil fish. Some variants add herbs and spices. For modern fish sauces, fish or shellfish are mixed with salt at a concentration of 10% to 30%. It is then sealed in a closed container for up to two years. Once the original draft has been made, some fish sauces will be produced through a re-extraction of the fish mass via boiling. To improve the visual appearance and add taste, second-pass fish sauces often have added caramel, molasses, or roasted rice. They are thinner, and less costly. Some volume manufacturers of fish sauce will also water down a first-press to manufacture more products. Fish sauce that has been only briefly fermented has a pronounced