How to Tell If Salmon Is Bad or Has Gone Off

Salmon is one of the most popular types of fish to eat in the U.S., with the national Fisheries Institute estimating more than 640 million pounds of salmon was consumed across the country in 2012.

As well as tasting delicious and working in a variety of dishes, salmon is also nutritious. The fish contains a great deal of protein, vitamin B12 and omega-3 fatty acids which are beneficial for eye and heart health.

While there are many reasons to add the fish to your menu, it is vital to handle seafood carefully to avoid the risks of foodborne illness.

Lisa Robinson, vice president for food safety and public health at food hygiene company Ecolabs, gave Newsweek her advice on how tell if salmon has gone off.

How to Know If Salmon Has Gone Bad

Although a key way to work out whether salmon has gone bad is based on its appearance, smell also plays a part in deciphering whether it is safe to eat.

There are also differences between fillets and whole fish, so there are particular things to look out depending on what cut of salmon you have.

Robinson told Newsweek: "Fish should smell fresh and mild, not fishy, sour, or ammonia-like. A fish's eyes should be clear and shiny. Whole fish should have firm flesh and red gills with no odor."

When it comes to fillets, the same rule applies to many different types of fish: the flesh should be firm and spring back when pressed. Fresh fish should also have red blood lines.

Other than smell and touch, ways to tell your salmon fillets may be out of date could be from a milky residue or spotting on the flesh, as well as general discoloration. If it begins to look pale rather than its usual vibrant color, this can be a sign your fish is out of date.

The Food and Drug Administration (FDA) also explains that while these characteristics (such as bloodlines), may not be present on "previously frozen" fish, your salmon should still smell fresh and mild.

Stock image of salmon
A stock image of raw salmon fillets with seasoning, about to go in the oven Getty Images

How to Store Salmon

Fish must be kept cold, so ensure you keep it in a refrigerator or on ice to remain safe.

It is important not to wait until your grocery shopping is done, but get the fish in the cold as soon as possible.

Robinson said: "If salmon will be used within two days after purchase, store it in a clean refrigerator at a temperature of 40°F or below."

Many fish eaters, however, may wish to buy their fish ahead of time, meaning it may need to be used later than two days.

As a result, knowing whether there are other storage options for fish is crucial in avoiding waste.

Stock image of salmon
A stock image of raw salmon fillets among other fish in a refrigerator Getty Images

Can Salmon Be Frozen?

Salmon can be frozen, and in the same way as the refrigerator, it is important to get the fish in the cold as soon as possible after purchasing.

To do this, wrap the salmon tightly in a moisture-proof wrap, such as plastic or foil, then place it in the freezer.

However, cooking fresh fish from frozen is not advised, and Robinson suggests multiple ways to defrost your fish before cooking.

She explained: "Thaw frozen seafood gradually by placing it in the refrigerator overnight. If you have to thaw seafood quickly, either seal it in a plastic bag and immerse it in cold water, or — if the food will be cooked immediately thereafter — microwave it on the defrost setting and stop the defrost cycle while the fish is still icy but pliable."

Before attempting to cook the salmon, it is important to get it to a point where the flesh is pliable.

The internal temperature of a salmon fillet should hit 110-125 Fahrenheit in order to to be safe to eat.

Stock image of salmon
A stock image of raw salmon fillets Getty Images