How to Tell if Salmon is Bad [Definitive Guide]

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Spoiled fish that has gone bad can cause serious illness, even hospitalization in some extreme cases.

But how do you know if your fish is ‘bad’? Are there any physical signs, like appearance, smell, or texture? Is there a limit on how long you can store salmon in the fridge or freezer? Not to mention how do you keep your salmon to prevent it from going bad.

These are the types of questions we’ll be discussing in this article, along with a detailed description of how to identify bad salmon – so you’ll never get caught buying dodgy salmon, or spending time locked in the bathroom.

How to Tell if Salmon is Bad

Let’s dive straight into it; bad salmon is something you’ll know when you come across it. Where fresh salmon, whether that’s a fillet or the whole fish laid out at your fishmonger or supermarket, looks quite different to salmon that has gone bad.

A whole fresh salmon will be firm, with the flesh firm against a probing finger and no limp tail or bendy bits. It will also have clear eyes and no ‘fishy’ smell at all.

It will have a subtle sheen to its scales, and your vendor should be able to tell you when/where it was caught or farmed.

Fillets or cutlets of fresh salmon will be bright dusky-orange, kind of like a summer sunset. There will still be no ‘fishy’ smell, and if there’s any skin on the piece, it will feel rough to the touch, with no slime present.

The flavor of fresh salmon is also unmistakable – clean, smooth, and some would describe it as luxuriant.

When it comes to spoiled salmon, the first thing you’ll notice is the smell. It’s overpoweringly fishy, sour, and has a distinct ammonia smell.

Bad salmon will also look strange. Where your fresh whole salmon will have a stiff body and clear eyes, a less-than-fresh salmon will be limp and its eyes cloudy.

More than likely, you’ll also notice a ‘milky’ film over the fish, kind of like a slimy membrane that doesn’t wipe off easily with your finger. 

This slimy milky film is different from the ‘white’ you’ll see between the flakes of raw or that oozes from a fillet of cooked salmon. That ‘white’ stuff is a protein called albumin. Albumin is what’s inside the whites of eggs (albumen), turns the ‘whites’ white when cooked. Good news, it’s safe to eat.

A fillet of salmon should have a bright dusky-orange color, but bad salmon will look pale and like a faded peach color. You may also see discoloration, or brown spots on the flesh, kind of like faded freckles.

Should you not notice any of these signs, the taste of rotting salmon is unmistakable. It will have an overpowering ‘rotten fish’ flavor that is sour and slimy in your mouth.

How to Tell if Salmon is Bad After Cooking  

Now know what to look for when choosing to buy fresh salmon. But, what about after the salmon has been cooked? What does should cooked fish look like, and how do you tell if salmon turns bad after it’s cooked? 

To start with, make sure your salmon is properly/fully cooked. Salmon cooked when it reaches an internal temperature of 145˚F/63˚C. You can check this by placing a thermometer probe into the thickest part of the flesh. 

You’ll also be able to tell your salmon is cooked by using a fork to ‘flake’ the fish; the individual flakes of salmon will easily separate from each other. 

Of course, the easiest way to tell is by looking at the middle of the fillet; if it’s still that gorgeous dusky-orange color, but opaque and easy to flake, then it’s cooked!

If the fish is partly opaque, and still partly bright, and feels firm when you poke it, it’s not quite done yet, and shouldn’t be eaten as is.

Salmon can and will go bad quickly after it’s cooked. Basically, you have a stopwatch running as soon as your salmon reaches its ‘cooked’ temperature and is taken off the heat. 

As the temperature begins to drop, you create an environment where bacteria breed. That bacterium is what will turn your salmon bad and making you ill if you eat it. 

Bacteria will form on salmon that’s left out on a kitchen counter within a matter of hours. Ideally, you want to refrigerate your salmon as soon as possible – placed it into an airtight container and chill in the fridge.

If it’s bad, it’s going to smell overly fishy, and a little sour. It will also have a weird color. That dusky orange will look ‘white-ish and may also have brown spots, or strange discoloration that’s easily visible.

Should you be unfortunate enough to put bad salmon in your mouth, you’ll taste the ‘off’ fish instantly. It will taste rotten, strongly of fish, and have an ammonia flavor as well. As mentioned before, eating bad salmon will make you ill, so it’s best to get rid of it asap.

How Long Does Salmon Last

This depends on where and how you’re keeping it.

If like most people, you’ve bought your fillet of salmon from the supermarket, there will be a ‘Best Before’ or ‘Use By’ date on the package. Don’t ignore this date. Whilst Best Before dates and Use By dates are guides, they do give a reasonable indicator of freshness.

Using your sensory clues (appearance, smell, etc) and the packaging date, you can then attempt to judge how soon your salmon should be eaten. Most fresh seafood is best consumed sooner rather than later. 

One key is keeping it cold. Raw salmon should always be stored in either the fridge or freezer and definitely below 40F/4˚C. 

As a general rule of thumb, fresh raw salmon should only be kept for 1-2 days after the ‘Best Before’ date before eating. Again, a quick check will confirm if the salmon is bad or not.

If your salmon has been frozen, then you have a bit more time to work with. Freezing fish is a great option to increase its shelf life, and fish can be stored this way for 2-3 months.

However, once thawed the salmon should be eaten within 1-2 days at the most. Thawing of the salmon should also be done in the fridge, and not at room temperature. If thawed at room temperature, thus over a longer time, bacteria will form and spoil the salmon.

What about smoked salmon? Or salmon preserved in vacuum-sealed bags? 

You’ll be pleased to know that there is more shelf life for these products. Smoked salmon, whether hot smoked or cold smoked, will last longer as it has been ‘cured’. 

Essentially, that means that the moisture within the salmon has been removed through osmosis, often by using ingredients like salt or sugar. Without that moisture, bacteria will struggle to breed.

Vacuum sealing cured salmon also removes any oxygen from coming in contact with the meat. This again increases the difficulty for bacteria to form, as they will not be able to breathe.

An unopened packet of smoked salmon will last for 2-3 weeks in a fridge that’s under 40˚F/4˚C. Whereas an opened packet of smoked salmon should be consumed within 3-4 days.

Kept in a freezer, smoked salmon will keep for 2-3 months at its best quality, but if it can be kept below 0˚F/-18˚C, it will keep indefinitely. 

How to Store Salmon

How, and where, you keep your salmon will have a big influence on its shelf life. The most common storage options are: fridge, freezer, or cured – hot or cold smoked, or even preserved with dill, salt and sugar.

When it comes to storing your salmon in the fridge, there are only a few basic principles to follow. First, ensure your fridge’s temperature is set correctly. 

The temperature of your fridge will affect everything stored in it – you may have already noticed food spoiling quicker than you expect. To keep fresh food as long as possible in your fridge, it must be set to below 40˚F/4˚C. 

Above 40˚F/4˚C and your food will start to spawn bacteria, and this is what spoils your food. The warmer the temperature, the quicker the bacterium grows, the sooner your food rots.

The second factor to remember is air. If you remove the oxygen, any lingering bacteria cannot breathe and will prevent it from growing.

For the best fridge storage, keep your salmon in its commercial packaging – factory sealed. Or, if you have bought a side of salmon, portion it into the required pieces, and get it into airtight containers or bags.

Once airtight, you can store your salmon in the fridge for several days, or you can store it for longer in the freezer. Over time, your frozen salmon may develop ‘freezer burn’, and this is especially likely if it comes into direct contact with frozen surfaces. 

To prevent freezer burn from happening, double-wrap the salmon in extra-thick foil or plastic. This thicker layer will reduce the risk of burning, and help keep your salmon at its optimum.

Of course, you can also preserve your salmon by using traditional methods; hot or cold smoking, and curing with salt. These two different curing methods have been carried out in many cultures for eons, and have a fantastic history.

Hot or cold smoking involves exposing the salmon to smoke that is either hot (being closer to the heat source), or cold (further away from the source and allowed to cool down). This smoke then infuses the salmon with its smoky flavor and prevents bacteria from forming. 

Preserving with salt, or salt/sugar is equally as old and is a simple process. Using plain salt or salt and sugar, the salmon is encased and allowed to dry out until little to no moisture is left. 

To Sum Up

 If it looks weird, or smells overly fishy or sour, and has a funky slime on it, it’s bad!

Fresh raw salmon should be bright orange, firm to the touch, and in the case of a whole salmon, it should have no slime and clear eyes. Fresh fish will never smell fishy.

Ultimately, fresh salmon will only last a few days in your fridge, or a few months in the freezer. The key to keeping your salmon as long as possible is to remove as much oxygen as you can and keep the storage temperature below 40˚F/4˚C.