Start With a Question, Not a Shopping List

Arriving at a harbour market with a recipe already in mind is the quickest way to be disappointed. You want brill for a Friday supper; the boats landed hake and gurnard. You want crab; the pots came up empty because of the wind. The stalls that sell best are the ones where the shopping list bends to the catch, not the other way round.

The first thing to do at any harbour market — whether it is a tin-roofed shed on a quay, a row of trestles beside a slipway, or a proper covered market hall a few streets back from the water — is to walk the whole place once before you buy anything. Look at what is on display, what is moving, and what the locals are queueing for. That queue is your best guide.

Ask What Was Landed Nearby

Once you have your bearings, talk to the people behind the counter. They are almost always the ones who bought the fish off the boat that morning, or they know the skipper by name. A few questions will tell you everything you need:

• "What came in last night?" This separates fresh landings from fish that has been sitting in a wholesale chain for three or four days.
• "What's from round here?" Local waters mean shorter journeys, less handling and, usually, a better price.
• "What would you take home tonight?" Stallholders are proud of their stock and rarely shy about pointing you at the best of it.
• "When was it iced?" A straight answer is a good sign. A vague one is not.

Day boats — the under-ten-metre vessels that go out and come back within a tide — are the heart of this trade. Their catch is often sold straight off the quay or through a small co-operative, and it rarely travels more than a few miles. If you see a chalkboard listing landings by boat name, read it. If a stall opens at six in the morning and is packing up by eleven, get there early; the good stuff goes first.

Judge the Fish Yourself

You do not need to be an expert to buy well. Four checks will carry you most of the way.

• Eyes. They should be clear, black and slightly domed. Cloudy, grey or sunken eyes mean the fish is old, however charming the stallholder.
• Smell. Fresh sea fish smells of the sea — clean, faintly saline, almost like a cold beach. Ammonia, sour milk or a metallic tang is a hard no.
• Flesh. Press a fillet or the flank of a whole fish with a fingertip. It should feel firm and springy and the indentation should fill back almost immediately. If your finger leaves a dent, walk away.
• Skin and scales. Scales should be tight and shiny, the skin glossy and taut, with no slime that feels thick or tacky rather than slippery-clean.

For whole fish, check the gills if you can — bright red or pinkish, never brown or grey — and look at the belly. It should be firm and intact, not soft, split or discoloured. For fillets, look for translucent flesh with no gaping along the flakes, no brown edges and no milky liquid pooling in the tray. If you are unsure, ask to see the whole fish it came from. Any decent stall should have some on the slab.

Know What to Expect Around the Coast

British and Irish waters give you a rolling calendar, and buying with it is both cheaper and tastier. Mackerel, herring and bass are at their best in the warmer months, though mackerel is superb almost year-round in the south-west. Autumn and winter bring the flatfish — plaice, lemon sole, dab — along with hake, whiting and the big shoals of herring in the North Sea. Pollack, gurnard, ling and coley are underrated, plentiful and often half the price of cod or haddock; they take to the pan beautifully.

Look out for regional specialities that rarely travel: Cornish sardines, Manx queenies, Scottish langoustines, Norfolk crabs, Kentish native oysters, Welsh laverbread. If it is on the slab and you cannot buy it at home, that is the fish to have for supper.

Don't Overlook the Shellfish

Harbour markets excel at shellfish. Choose live crabs that feel heavy for their size, with all their legs and claws attached and no black spots on the shell underneath. Mussels should be tightly closed; tap any that are open and discard those that do not shut. Native oysters are flat-shelled and expensive, rock oysters are deeper and cheaper — both should smell of the sea and nothing else. Scallops are best bought in the shell with roe attached, and if you can find out whether they were hand-dived or dredged, so much the better.

Get It Home and Cook It Simply

Ask the stall to gut, scale and fillet for you — most will do it at no extra charge. Take a cool bag and a freezer block, and never let fish sit in meltwater; it should be kept cold and dry, wrapped in paper or a cloth, with ice beside it rather than beneath it. Cook white fish within a day or two, oily fish within a day, and freeze anything you cannot manage.

And keep the cooking simple. A whole mackerel on a hot barbecue, a gurnard baked in a tray with tomatoes and olives, crab on buttered white bread with a squeeze of lemon, scallops seared for ninety seconds a side. Fish this fresh needs seasoning, heat and not much else. If you got the buying right at the harbour, the cooking looks after itself.