Naples loves its fish so much even the aquarium gets raided

The mature and sensibly clad visitors waiting to be admitted to the Gabinetto Segreto, the room of erotica at the national museum in Naples, have walked straight past the real turn-on. Before the mosaics of naughty bath-times and a frisky vase painting, they have overlooked a scene of more writhing, slithering and entwining than could be devised in the most feverishly fertile mind. For the ultimate sensation, forget fornication – the Neapolitan loves fish.

The mature and sensibly clad visitors waiting to be admitted to the Gabinetto Segreto, the room of erotica at the national museum in Naples, have walked straight past the real turn-on. Before the mosaics of naughty bath-times and a frisky vase painting, they have overlooked a scene of more writhing, slithering and entwining than could be devised in the most feverishly fertile mind. For the ultimate sensation, forget fornication – the Neapolitan loves fish.

The mosaic salvaged from Pompeii is one of a shoal of images of fish spawned by the city's infatuation with its scaly neighbours. In a tapestry at the Palazzo Reale, Neptune crashlands on the shore in a chariot pulled by horses with fishtails, shovelling a feast on to the beach: lobsters, crabs, turtles, skate, catfish and dogfish. The frieze of harpoons and empty shells suggests a before-and-after narrative. A few rooms away a gigantic Nativity crib scene has not only its traditional complement of shepherds and kings but also a fishmonger.

A devoutly Catholic population is perfectly at home with Christian images – Peter, the fisher of men, loaves and fishes for the five thousand, empty nets miraculously crammed to overflowing. Stories that have a fairytale air to most city-dwellers smack of everyday life to a community which lives, economically and geographically, by the sea.

A trip to the Villa Communale affords access to the aquarium, more visited by boggle-eyed Italians than byforeigners who expect to tick off churches and art galleries on their travels, not to retreat from the sun to a damp and dark netherworld. In this case swim fish translucent and striped, garish or secretive. The thick-lipped black umber seems to be made of stone; a beach pebble with fins. The scorpion fish is a confection of caramel, cream and raspberry perfectly camouflaged on a miniature seabed of crustacea. Mean-faced moray eels peek out of submerged terracotta jars; a self-potting eel, the lazy gourmet's delight. The eagle ray, elephant's ears on a stick, circuits its inadequate home again and again, skimming the edges like a skater.

The pesce balestra (literally, crossbow fish), is known in English as the grey trigger fish. Trust the English to highlight the grey. Better to mention that the male looks after the eggs: fish lib. The salpa (salema) has gone one better, starting life as a male and becoming a female with maturity, while the pagello fragolino, or common pandora goes the other way, being born female and transforming into a male. The spigola (sea bass) throws itself into an orgy of ejaculation, the males and females releasing eggs and sperm into the water simultaneously. Seahorses dance, then the female donates eggs into the male pouch; the balesra opts for a one-night stand.

And all the time the talk is of food. "Si mangia?" "Can you eat them?" The answer, by and large is yes: at the end of the war in a banquet for the victorious allies, the aquarium's most prized possession, a baby manatee, was served up with garlic sauce. On the last wall of the exhibition there is a display board: "Are jellyfish good to eat?" This must be the only natural history museum in the world where there are instructions on how to devour the exhibits.

The key to culinary success when confronted with a lump of jellyfish is to combine 200g with a whole chicken and a coconut, plus lemon, lettuce and carrot. Boil for three hours. Serves six. Recipes go back centuries. The poet Horace records Curtillus's sauce, a mixture of garlic, anchovies and olive oil – and between 50 and 70 sea urchins. Or take Nasidenus's shrimp and wine sauce: magic ingredient, eel. If, like the locals, this gives you an appetite, the most scenic place to go is the Castel dell'Ovo district.

Surrounded by thick, working water, are restaurants backed by Vesuvius. In via Luculliana at the Antica Trattoria da Pietro, by 4:30pm the lunch trade is trailing off and a four-generation family relaxes. A teenage daughter appears with her top rolled up and skirt pushed down to reveal an ample, bronzed midriff. Her grandfather is stooped over a blue plastic bucket, sorting mussels. Meanwhile baby Pietro has been wheeled to feed, not the ducks but the fish.

Drop into any Naples eatery and fish come as standard. Even bruschetta is served with mussels. When the whitebait runs out at Da Tonino in Piazza della Carita, a tray is brought with samples of near relatives. The linguine with seafood at Transatlantico is a riot of eyes and claws. Fish are plug-ugly. Goggle-eyed, bash-mouthed, spiney, spiky, jutting; either too smooth by half or too craggy for comfort. Wondrous, yes. Acrobats unquestionably. But not beautiful, not by the usual standards. With a few exceptions, fish squabble for first prize at the Ugly Mug Ball.

The principal fish market is behind the church of Santa Maria del Carmine, where tiny edible imports from nimble shrimps to muscular octopuses lurk in buckets and bowls, bathed in water and ice, garnished with seaweed and lemon, ready for the frying pan and the grill. But, towards midday on a summer's morning, there is nothing whiffy in the air. This stuff is so fresh it only smells of the sea.

Slippery transactions take place daily in the shadow of Santa Chiara. It was here in 1647 that protesters met when the poor rebelled against taxes on fruit-growing. Their ringleader Tomasso Aniello became a martyr. True he was marching for cheaper fruit, but this is Naples: he was a fisherman.

The Facts

Getting there
Go (0870 607 6543; www.go-fly.com) flies to Naples from £78 return. Bed and breakfast for two at the Hotel Royal, 38 Via Partenope, 80121 Naples (0039 081 245 2068; www.hotelroyal.it) from €182 (£115) per night. Italian State Tourist Board (020-7408 1254; www.enit.it).