Comacchio Eel

The European eel, Anguilla anguilla, has a life cycle that sounds made up. It spawns in the Sargasso Sea, in the middle of the Atlantic. The larvae drift on the currents for one to three years until they reach Europe, where they become glass eels, transparent and six or seven centimetres long, and push up the river mouths into brackish lagoons.

There the eel stays for years, yellow-bellied, feeding and growing. Then it changes: the back darkens, the flanks turn metallic, the eyes enlarge, the gut atrophies. This is the silver eel, ready to return to the Atlantic, spawn once and die.

Two practical consequences follow. Nobody has ever observed European eels spawning in the wild, and the species cannot be bred in captivity at commercial scale, so every farmed eel on earth began as a wild-caught glass eel. And the fishery at Comacchio is built entirely on the migration, because an eel heading for the sea has to pass through one place.

Comacchio produces two things. Fresh seasonal eel, grilled over embers or stewed. And marinated eel, roasted on spits then packed in vinegar, is the historic product shipped across Italy for centuries and now a Slow Food Presidium.

Rich. Silver eel can carry more than twenty per cent fat, and the flesh is dense, white and unctuous, closer to pork belly than to any lean fish. There is no fishiness and no iodine; the flavour is deep, slightly sweet and faintly earthy from the brackish water.

Grilled over embers, the fat drips away and the outside caramelises while the inside stays soft. It is one of the very few fish that behaves like meat on a barbecue.

The marinated version tastes completely different. Roasting first, then weeks in wine vinegar, water, salt and bay leaves, cuts the richness and firms the flesh: what you get is cold, sharp, savoury and slightly smoky, eaten in small pieces with bread or polenta. The register is closer to soused herring or escabeche than to anything Italians usually eat.

Anyone who knows Japanese unagi will recognise the texture and be surprised by the direction of the seasoning. Japan sweetens eel with soy and mirin; Comacchio sours it with vinegar. Same fat, opposite strategy.

Eel is a fat fish and every traditional treatment is built around that fat: fierce heat, acid, and nothing creamy anywhere near it.

Over embers is the most direct route. Thick sections on the grill, salt, a bay leaf between the pieces, and the fat dripping onto the coals. Serve with polenta and something sharp on the side.

Stewed is the Comacchio home version: a soffritto, tomato, long slow cooking, white polenta alongside. Risotto made with a stock from the heads is the lagoon variant.

Marinated eel is eaten cold, as an antipasto, with bread or grilled polenta. Do not warm it: heat undoes what the vinegar firmed up and you end up with something slack.

Two warnings. Raw eel blood contains a protein toxin that irritates skin, eyes and mucous membranes and is destroyed by heat, which is why eel is always cooked and never served raw anywhere in the world. And the skin is thick and rubbery; it is usually removed before cooking, except over coals, where it protects the flesh and is left on.

Fresh eel is a same-day fish. If it has to wait, one day in the fridge, already gutted, wrapped in paper rather than sealed in plastic, which holds moisture against the skin. Cut into steaks it freezes for two or three months, and the limit is the fat rather than the flesh: a silver eel is very fatty, that fat oxidises in the freezer, and past three months the flavour turns and takes on a rancid edge no cooking removes. The fishmonger and the date on the label are the reference for anything beyond that.

A sealed jar or tin of marinated eel keeps twelve to eighteen months somewhere cool and dark, to the date printed on it. Once it is open it goes into the fridge with the pieces always under the liquid, and it is worked through over two or three weeks; any piece standing above the marinade dries at the edge and darkens within a day. When the liquid runs low, top it up with wine vinegar and water in the same proportion as the original, never with water alone, which dilutes what is holding the pieces.

Fresh eel is bought alive or just killed. The skin glossy and slippery, the body firm and reacting to the hand, the eye full and domed; a slack body, dull skin and a muddy smell that will not shift are signs of time spent out of the water. It helps to know which life stage you are looking at. A yellow eel has a yellowish belly, a small eye and leaner flesh. A silver eel has a dark back, metallic flanks, a large eye and far more fat, and it is the autumn fish, built for the grill and for marinating.

On the marinated product, check three things: the pieces should be compact rather than flaking, the marinade clear rather than cloudy, and bay leaf visible in the jar. The label should give the zone of origin, and traditional producers reference the Slow Food Presidium. The words anguilla marinata alone say nothing about where the fish came from, which may be a farm at the other end of Europe. Abroad you meet smoked eel from the Netherlands or Denmark, London jellied eel, or Japanese unagi, all different preparations.

Start with the conservation reality: the European eel is Critically Endangered on the IUCN Red List, glass eel recruitment has collapsed to a small fraction of 1970s levels, the species is on CITES Appendix II, and EU rules impose national management plans and closed seasons. This is an occasional food, not a weekly one, and glass eels should be left alone entirely.

If you do buy it, buy traceable. In Italy, the Slow Food Presidium producers at Comacchio sell marinated eel in jars and tins, and specialist delicatessens stock it seasonally. In the UK and the Netherlands, established smokehouses sell hot-smoked eel and some can document their source. In the US, Japanese suppliers sell frozen glazed unagi, and a few importers carry European marinated eel.

Prices: fresh eel runs 12 to 22 euros a kilo, more like 20 to 30 for wild lagoon fish in season, roughly 6 to 15 dollars per pound, or 10 to 26 pounds per kilo. Marinated eel in jars runs 40 to 60 euros a kilo, so 9 to 16 euros for a 200 to 300 gram jar.

On the label, look for the origin of the fish and, for the traditional product, the Presidium reference. The words marinated eel alone say nothing about where the fish came from, and most eel sold in Europe is farmed, which still means wild-caught glass eels at the start of the chain.

Comacchio itself: a small town built on water, with canals instead of streets and the seventeenth-century Trepponti bridge at its centre. The Manifattura dei Marinati is both a museum and a working plant: in season you can see the fires lit and the spits turning in the long hall of hearths. The Museo Delta Antico holds the cargo of a Roman ship found in the lagoon.

In autumn the town runs an eel festival across several weekends, which is the simplest way to eat the whole repertoire, from the grill to the jar. Boat trips leave for the old fishing stations and the isolated casoni out in the lagoons, where flamingos are now permanent residents.

Twenty kilometres away are the beaches of the Lidi di Comacchio; inland is Ferrara, whose Renaissance cooking has nothing to do with eel and is worth a day on its own. All of it sits inside the Po Delta Park.