Quick Answer: Judge a fish counter by smell first — it should smell of clean sea, never of fish — then check that whole fish are buried in ice rather than sitting on it, that eyes are clear and domed, that fillets look translucent rather than chalky, that there is no standing liquid in the trays, that staff can tell you what came in today, and that the counter turns over enough stock to justify its display size. Any two failures is enough to walk.

The single best predictor of whether fish will be good at dinner is not the species, the price, or whether it says fresh on the label.

It is the counter you bought it from — and you can assess that in half a minute without asking anyone anything.

Here are the seven signals, roughly in the order you encounter them walking up.

The fifth one is the tell that separates a genuinely good counter from one that merely looks good.

1. It smells of the sea, not of fish

This is the first signal and the most reliable one.

Truly fresh fish smells of clean seawater, cucumber, or almost nothing. The fishy smell people associate with seafood is a decomposition product — trimethylamine, which forms as the fish breaks down.

So a counter that smells fishy is telling you directly that something on it is past its best, and by the time you can smell it from a metre away, it is not marginal.

Trust this over everything else on the list. A counter can look immaculate and still fail this test, and when the two disagree, the nose is right.

2 and 3: Ice coverage and the eyes

2. Whole fish are buried in ice, not resting on it

Fish needs to be at or just below 0°C, and the only practical way to hold that at a display counter is contact with ice on all sides.

Look for fish nestled into ice with ice packed around them, ideally with some flaked ice over the body. Fish lying on top of a flat ice bed is being chilled on one side and warmed by air on the other.

The rate of spoilage roughly doubles for every few degrees above freezing, so this is not a presentation detail. A fish held at 4°C rather than 0°C loses days of shelf life.

Good counters restock ice through the day. If the ice looks melted and glassy at 4pm, the fish has been sitting warm for hours.

3. Eyes are clear, domed, and black

The eye is the fastest-degrading visible part of a whole fish, which makes it an excellent early indicator.

Fresh: clear, slightly bulging, with a black pupil. As the fish ages the eye flattens, then sinks, and the surface clouds to grey.

There is one honest exception — some deep-water species and any fish that was iced roughly can have cloudy eyes while still being fine. So treat cloudy eyes as a reason to check gills and smell rather than as an automatic no.

Gills are the confirmation. Lift the flap: bright red to deep pink is good, brown or grey is not, and slimy grey is well past it. Any counter worth buying from will let you look.

4. Fillets look translucent, not chalky or gaping

You cannot check the eyes of a fillet, so the signals are different.

Fresh fillets have a translucent, almost wet-glass quality and the flesh looks continuous. As they age they turn opaque and chalky, and the muscle blocks begin to separate — a phenomenon called gaping, where you can see gaps opening between the flakes.

Gaping is the one to watch for. It means the connective tissue has started breaking down, and that fillet will fall apart in the pan no matter how carefully you cook it.

Also check the cut edges. Dried, slightly browned edges mean the fillet has been sitting exposed to air, which happens on slow-moving counters even when the temperature is right.

5. There is no standing liquid in the trays

Here is the one that separates good counters from merely tidy ones.

Pooled liquid around fillets is drip loss — fluid that has come out of the muscle. It happens with age, with temperature fluctuation, and above all with fish that has been frozen and thawed without that being disclosed.

A little moisture is normal. A visible pool is not. And it is a compounding problem: that liquid is a bacterial growth medium sitting in direct contact with everything in the tray.

This also catches counters that thaw frozen fish and sell it as fresh. That is not necessarily bad fish — frozen-at-sea is often better than five-day-old fresh — but a counter that will not tell you is a counter making other decisions you cannot see either.

6 and 7: The staff, and the size of the display

6. Staff can tell you what came in today

Ask one question: what came in today?

A good counter answers instantly and specifically — this came Tuesday, that one is from this morning, the scallops are yesterday’s and I would use them tonight. They will often steer you away from something, which is the strongest possible signal.

A weak counter says everything is fresh, which is a non-answer.

The steering-you-away behaviour is the real test. A counter that tells you the fish you asked for is not at its best today, and suggests something else, is a counter that expects you to come back. That is worth more than any display.

7. The display is sized to the turnover

A large, beautifully full counter in a shop with no customers is a warning, not a reassurance.

Fish is display stock. It sits there all day, and whatever does not sell has to go somewhere. A small counter with six species that sells out is far better than a big one with thirty that does not.

Watch the counter for thirty seconds. Is anyone buying? Is stock being taken from behind and replenished, or is it just being rearranged?

Best case, buy late morning: the day’s delivery is out, it has been properly iced, and it has not spent eight hours under lights. Worst case is the last hour of trading on a quiet day.

FAQ: Buying Fish Questions, Answered

Is frozen fish worse than what is on the counter?

Usually the opposite. Frozen-at-sea fish is often processed within hours of catching, while counter fish may be four or five days from the water. For anything you are cooking through rather than eating raw, good frozen fish beats mediocre fresh fish comfortably — and it costs less.

How long can I keep fresh fish at home?

Cook it the same day or the next, and store it on ice or at the very back of the bottom shelf, which is the coldest part of a fridge. If you are not cooking it within a day, freeze it immediately rather than waiting to see — a fillet frozen on day one is far better than one frozen on day three.

What if my only option is a supermarket counter?

Apply the same seven checks, which work identically. Supermarket counters vary enormously, and the ones with high turnover in busy stores are often excellent. If yours fails the tests, the frozen section of the same shop is very likely the better buy.

TL;DR:

• Smell first. Clean sea or nothing is right; a fishy smell means decomposition, and it overrules a good-looking display.
• Whole fish should be buried in ice, with clear domed eyes and red gills — melted glassy ice at 4pm tells you what the day has been like.
• Fillets should be translucent with no gaping, and no pooled liquid in the tray — that pool is the sign most people miss.
• Ask what came in today. A counter that steers you away from something is the best signal available.

Two failures and walk — the frozen aisle in the same shop is very often the better buy, and there is no shame in it.