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How to Tell if Fish Has Gone Bad

To tell if fish has gone bad, consider the sell-by date printed on the packaging, the texture, and the smell of the fish.

Fish should be stored in a freezer or refrigerator for a limited timeframe. However, the meat will eventually spoil, at which point it will be unsafe to eat.

Unlike chicken or beef, fish are aquatic creatures that can spoil quickly, especially in a warm climate.

To avoid food poisoning, discard fish once it shows signs of spoilage.

Check Sell-by Date

On the packaging, carefully read the sell-by date. Discard any fish if it’s been more than a day or two since that date.

Raw fish does not keep well in the refrigerator and goes bad quickly after the sell-by date.

If you want to extend the shelf life of the fish, place it in the freezer rather than the refrigerator.

If the fish has a use-by date rather than a sell-by date, do not keep it after that date. The use-by date shows that if you don’t consume the fish before this date, it will ultimately spoil.

Similarly, if you buy or cook your own cooked fish and store it in an airtight container in the refrigerator, it will last longer than raw fish.

However, if you haven’t eaten the fish within 5 or 6 days of the sell-by date, it must be discarded.

If you know ahead of time that you won’t be able to use the cooked fish before it expires, store it in the freezer to extend its life.

Alternatively, write the sell-by date so you don’t forget it after you’ve discarded the packaging. Write the date on a notepad and put it somewhere on the door of your refrigerator.

Placing your fish in freezer, whether raw or cooked, will keep much longer than refrigerator.

Inspect the Fish

Raw fish develops a thin layer of slime as it ages and deteriorates.

This is a sign that your fish has spoiled. Once the fish has spoiled completely, the slimy moisture on the meat will feel thick and slippery to the touch.

If you notice this slimy texture, discard the raw fish immediately. Cooked fish will not develop a slimy coating, even if it has spoiled.

All fish, whether raw or cooked, smells like fish. However, refrigerated fish that has spoiled will emit an increasingly fishy odor.

Given enough time, this fishy odor will mutate into the putrid odor of rotting meat. As the fish spoils, the smell becomes stronger and stronger.

In addition, fish meat is typically light pink or white, with a thin, clear liquid film on top.

The meat of fresh or refrigerated fish will turn a bright, milky color as it ages and spoils. The milky parts of the fish may also have a blue or grayish tint.

If your fish has already been cooked, it will not develop a milky color. This only applies to raw fish. If you have a whole fish, the eyes will appear cloudy if it has gone bad.

If you keep fish in the freezer for months, it may develop freezer burn. Look for crystallized ice peaks that have formed on the fish’s surface, as well as any discolored patches.

Through a process known as sublimation, these crystals travel to the surface of food and eventually burn it (1).

Food that has been frozen and burned is still edible and will not make you sick. However, as freezer burn sets in, fish will lose most of its quality (2).

Risks of Eating Spoiled Fish

Fish has a high risk of causing food poisoning. You should, however, avoid cooking and eating spoiled fish.

Spoiled fish can cause scombroid poisoning, which happens after consuming fresh, tinned, or smoked fish with high histamine levels because of faulty storage.

Scombroid poisoning symptoms may appear 10 to 90 minutes after consuming the rotten fish (3).

These include facial flushing (becoming red), palpitations, headaches, dizziness, sweating, nausea, vomiting, rashes, and abdominal pain.

These symptoms are like those seen in other allergic reactions. You are not allergic to fish if you have scombroid poisoning.

Call for emergency medical help if you noticed one or more of the above symptoms after ingesting fish.


Raw fish does not keep well in the refrigerator and spoils quickly beyond its expiration date.

Frozen fish, whether raw or cooked, has a much longer shelf life than refrigerated fish.

Fish meat is usually light pink or white, with a thin, clear film on top.

Fish that have been frozen for over 9 months may develop freezer burn.

When purchasing fish, it is critical that you thoroughly inspect it before it is wrapped.

Fresh fish will have no odor and will appear moist, glistening, and bright.

You don’t want to risk eating rotten fish since you’ll get food poisoning.

Naeem Durrani BSc
I am a retired pharmacist, nutritionist, and food system expert. My interests include medical research and the scientific evidence around effective wellness practices that empower people to transform their lives.


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