Any casual perusal of ancient Roman recipes will quickly reveal the mysterious ingredients liquamen and garum. This staple of Roman cooking is essentially a salty sauce made of decomposed fish though there is still some discussion about what liquamen and garum acutally represent.
Though the use of 'fish sauce' is synonymous with Roman cookery, it was invented by the Greeks who called it γαροσ (garos); from which the Roman name garvm derives. The Greeks may originally have invented the sauce out of a need to do something constructive with the large quantities of tiny fish they caught in their nets (fish too small to be consumed directly). Over the centuries the Greeks developed a taste for this sauce, using it both as a substitute for salt and as a flavour additive in their food. It is possible that it was made from the Mediterranean fish that the Greeks called garos. Contact between the Greek and Roman worlds (and the subsequent conquest of the Greeks by the Romans) brought garos to the attention of the Roman culinary sphere.
Unfortunately there are no historical records or writings about garum/liquamen before the first century CE. At this time the writings of Pliny the Elder infor us that garum was a liquid not unlike aged mead (honey wine) in appearance and which was often mixed with wine to drink. He tells us that it was made by mixing fish, fish intestines and salt together in sealed jars until it liquefies. Writing in the same century Martial informs us that garum was made from the blood of a still-breathing mackerel. This would seem to be little more than poetic license but it does suggest that fresh, rather than rotten, fish was used. It seems that fish sauce could be made from a single fish species or a mix of different fish. Martial tells us that mackerel garum was by far the best type. He also names muria as a fish sauce made from tuna but tells us that this was considered only of secondary quality.
As well as garum and liquamen we have now encountered muria and there was a more solid paste available as well, called allec. Undoubtedly there are differences between them. However, all result from the basic process of preserving fish with salt. Of course, we are familiar with the salting of fish today, though this is generally a rapid process of semi-drying. However, if the salt and fish mixture is left for long enough the salt draws all the water from the fish. This liquid contains sufficient sugars and proteins that fermentation can occur, a process that aids in the dissolution of the remaining solid matter. Essentially this is an anaerobic process and the fermentation process itself prevents the development of bacteris so that little or no decay or putrefaction is observed. The process is even more efficient if the blood and guts of the fish are included as these contain protease enzymes that aid in the breakdown of the fish flesh. There is also sufficient salt in the final liquid that bacteria cannot grow and the final sauce is essentially sterile. The remaining solid matter sinks to the bottom of the vessel that contains the sauce and it is this that the Romans harvested as allec.
As a process, the pickling fish in salt is dependent on a number of variables in that the ratio of salt to fish will affect the resulting sauce. Some recipes also call for the addition of different herbs and spices to the initial fish and salt mixture. Food historians have spent considerable time attempting to match the various descriptions of different kinds of fish sauce to the various names that have come down to us, without much success. It may well be that there was a standard form of fish sauce that everyone used as an addition to food and then there were several more expensive variants of this which were only used for and by the richest tables. It may well be that the main factor affecting the 'quality' of the fish sauce was its pungency, which was affected both by the species of fish used and by the ammount of blood and intestines added to the initial mixture.
Indeed, as Martial's writings have indicated and as Manilius I also suggests in his poem, the Astronomica a fish sauce could be made entirely from the blood and intestines of fish. Manilius I describes fish being brought whole onto the beach. These are cut up and the 'precious fluid' is saved and mixed with salt. This would suggest that all but the flesh of the fish was used at this stage. Indeed, he later says that two types of sauce are generated. One from the blood and intestines and the other from the fish's flesh. The latter form generates a deposit which he describes as a 'soft accompaniment to food'. This could only be allec and suggests that the fish-flavoured liquid above the allec might itself be used as a kind of fish sauce.
Manilius I also describes a further process whereby vast numbers of small fish are netted and poured into large wine jars called dolia. It has to be assumed that salt is added and that these jars are sealed. But was this really how the sauce was made? The problem is that though we have descriptions of garum relating to the first century CE the first actual recipe we have comes from the 10th century CE. This uses fish flesh as well as extra blood and calls the resulting sauce liquamen.
The term liquamen for fish sauce is unknown in the first century CE (when we have the first recorded references to garum) and this substance is known from Apicius' fourth century CE cookbook, De Re Coquinara. The term liquamen for fish sauce seems to arrive with Apicius and is used almost exclusively thereafter. Subsequent Medieval sources even tell us that garum and liquamen are the same thing. Many redactors of ancient recipes have suggested that garum was a solid fish paste and that liquamen was the liquid fish sauce. However, this seems unlikely as the term allec was in common usage for the former type of product. What, then, is the truth of the situation?
The Greek origin of garos is undisputed. This may originally have been a way of rendering something useful from waste fish intestines. Eventually small fish were added to the recipe which led to another form of fish sauce. With the conquest of Greece both products were imported to Rome and used extensively by slave Greek cooks. The Romans acquired a taste for these sauces and in an attempt at increasing the market the idea of making specialized sauces from individual species of fish is introduced. To maximize production the entire fish is now used in the sauce and this quality product retains the name of garum. A secondary product made from tuna (and possibly with the inclusion of other fish) is called muria. The name liquamen may have been the name given to the cheap everyday product made from small fish is named liquamen. This 'basic' fish sauce would be the standard ingredient used by everyone and thus would not be worthy of note for the gastronomes of the first century CE. However, as the Roman empire declined the call for the expensive single-species sauce declined and the term garum gradually fell into disuse. By the fourth century garum was no longer available and even the most expensive of palates had to use liquamen as the only product available.
Whatever the final product is like, the process of generationg garum/liquamen was very smelly. So pungent in fact that it was declared illegal to make garum in a private house. As a result the fish sauce was produced exclusively by garum factories along the Italian coastline. In actuality salting tanks for garum/liquamen production have been found all around the southern and south-western coasts of Iberia, from the Tagus and Sado Rivers to Cadiz. One of the largest concentrations of production facilities was found at Troia at the mouth of the River Sado, in Portugal. There were also smaller concentrations in the Algarve such as those at Boca do Rio, Praia da Luz, Lagos and Quinta do Lago. In terms of quality Lusitanian garum was considered the best and most superior product.
To be authentic you could make your own garum but a good substitute is the Thai fish sauce Nam Pla. And before the thought of putting fish sauce in just about everything makes you recoil in horror from the very thought of Roman cooking, its tast is hardly noticeable in most dishes. However, using fish sauce fits in with the Roman culinary ethos where wine, honey, vinegar, oil and fish sauce are combined to create a balance of sweet-sour-salt-umami that is quite unique. The true secret of fish sauce is that it does not simply supply salt to a dish it also supplies umami. This being the fifth basic taste that confers 'savoryness' to a dish; the full mouth feeling when eating cheese or anchivies. This is why Roman food is so tasty and if you forgo the fish sauce you will be missing one of the five basic taste components of the food. Please note as well that though anchovy paste or anchovy essence provides lots of umami flavour it is not a substitute for fish sauce. Indeed, recipes where anchovy essence has been substituted for fish sauce can turn out to be quite disgusting.
