How to identify fresh fish at a Kerala fish market

By the Cochimart Kitchen Desk · Published 20 October 2026

Why freshness matters so much with fish

Fish begins to change from the moment it is caught. The FAO's technical guide to fresh fish quality describes four stages for fish kept in ice. At first it is very fresh, with a sweet, seaweed-like character. Then it loses that character and becomes neutral but still pleasant. Next, bacteria start producing unpleasant-smelling compounds, including the one responsible for the typical "fishy" smell. Finally the fish is spoiled.

The good news is that most of these changes show up in ways you can see, smell and feel at the counter. Inspectors at landing centres and markets judge raw fish by appearance, texture and odour, and you can use the same checks. In Kerala this matters every day: mathi (sardine), ayala (Indian mackerel), neymeen (seer fish), karimeen (pearl spot) and chemmeen (prawns) are bought fresh, often in hot and humid weather. If you are unsure of a fish's Malayalam or English name, our Malayalam–English fish names list covers the common ones.

The quick checklist

1. Smell it first.
2. Look at the eyes.
3. Lift the gill cover and check the gills.
4. Look at the skin and its slime.
5. Press the flesh and the belly.
6. Check how the fish is being kept: on ice or not.

No single check is enough on its own. A fish that passes most of them is a good choice. A fish that fails the smell test should be left behind whatever else it looks like.

Step by step: what to look for

1. Smell

The US Food and Drug Administration (FDA) says fish should smell fresh and mild, not fishy, sour or ammonia-like. The FAO describes the smell of very fresh fish as like seaweed, sometimes slightly metallic. As fish ages that fresh smell disappears, then a sour smell appears, and later stale, rancid or ammonia notes. Smell near the gills and the belly, where changes show up early.

2. Eyes

In the European freshness grading reproduced by the FAO, the best fish have convex (bulging) eyes with a transparent cornea and a black, bright pupil. As quality falls, the eye flattens and then sinks, the cornea turns opalescent and then milky, and the pupil goes from black to grey. Clear, full eyes are one of the easiest signs to read in a busy market.

3. Gills

Lift the gill cover with a finger or ask the seller to show you. Fresh gills are bright red with no slime or only a trace of clear mucus. Older fish have gills that are fading and discoloured, then brownish or yellowish, with opaque or milky mucus. The FDA also lists red gills with no odour as a sign of fresh whole fish.

4. Skin and slime

Fresh fish skin has bright, shiny, often iridescent colour, covered with a thin, clear and watery slime. With time the colour becomes dull, and the slime turns cloudy, then milky and opaque. Scales that come off very easily and a wrinkled surface are signs of a fish well past its best.

5. Flesh and belly

Press the side of the fish gently with a fingertip. Fresh flesh is firm and elastic, and the FDA notes it should spring back. If your fingerprint stays as a dent, or the flesh feels soft and limp, the fish is older. The belly should also feel firm. A soft belly, or one that has split open, is a strong warning sign.

A fish that feels completely stiff is not a problem. Very fresh fish often go through rigor mortis, the natural stiffening after death, before softening again. Stiffness is a good sign as long as the eyes, gills and smell also pass.

6. Colour of fillets and steaks

For cut pieces, such as steaks of seer fish, the FDA says fillets should have firm flesh and red blood lines, with no discoloration, darkening or drying around the edges. It also warns that colour alone is not a reliable sign of freshness, because colour depends on many factors. Use smell and firmness as well.

7. Prawns and shellfish

For prawns, the FDA advises that the flesh should look clear with a pearl-like colour and have little or no odour. Prawns that smell of ammonia or look slimy should be avoided.

How the fish is kept matters as much as the fish

The FDA advises buying only fish that is refrigerated or displayed on a thick bed of fresh ice. The FAO adds an important point: fish that is chilled without ice may change less in appearance than iced fish but actually spoils faster. In other words, fish that looks fine but has been sitting out in the heat can be older in quality than it appears. In a warm Kerala market, choose a seller whose fish is properly packed in plenty of ice and kept out of direct sun.

Frozen and previously frozen fish

Much of the fish sold in Gulf cities and abroad has been frozen. The FDA notes that fish sold as previously frozen may not show every sign of fresh fish, such as bright eyes, firm flesh or red gills, but it should still smell fresh and mild, not fishy, sour or rancid. When buying frozen packs, the FDA advises avoiding packages that are open, torn or crushed, packs with frost or ice crystals (which may mean long storage or thawing and refreezing), and fish that is not frozen hard.

Getting it home safely

• Make the fish market your last stop so the fish is not left in a warm car or bag.
• The FDA advises putting seafood on ice, or in the refrigerator or freezer, soon after buying it.
• If you will use it within two days, keep it in a clean refrigerator at 40°F (about 4°C) or below. Otherwise wrap it tightly in plastic, foil or moisture-proof paper and freeze it.
• Keep raw fish and its juices away from ready-to-eat foods.
• If raw fish smells sour, rancid, fishy or of ammonia, the FDA's advice is simple: do not eat it.

Which fish are plentiful changes through the year. Our seasonal produce calendar covers what is in season, and the bilingual grocery list maker helps you note fish names in both English and Malayalam. For keeping dry ingredients at their best, see how to store spices, or browse all kitchen guides.

Sources and useful links

• US FDA: Selecting and Serving Fresh and Frozen Seafood Safely
• FAO (Huss): Quality and quality changes in fresh fish, ch. 5 Post-mortem changes in fish
• FAO (Huss): Quality and quality changes in fresh fish, ch. 8 Methods for freshness evaluation

Frequently asked questions