How To Tell if Swordfish Is Bad?

Swordfish is prized by many seafood lovers for its rich, slightly sweet flavor and meaty texture. I love it as a chef, because of its versatility in different cooking applications.

Because it is so popular, swordfish is expensive so you can imagine my concern when I got stuck in traffic one day with two swordfish steaks fresh from the grocery store stuck in the trunk of my car.

Before I could cook them, I had to make sure they were still good to eat, and I had not lost out on my purchase.

To determine if swordfish is bad, start by examining its appearance; fresh swordfish steaks should have a bright, slightly pink or ivory color with no signs of browning or gray spots. The texture is also a key indicator – the flesh should be firm to the touch and not slimy or sticky. Smell is another crucial factor; fresh swordfish should have a mild, ocean-like scent, and any strong, ammonia-like or overly fishy odors suggest spoilage. If the swordfish fails any of these tests – appearance, texture, or smell – it’s best to err on the side of caution and avoid consuming it.

How To Tell if Swordfish Gone Bad?

Swordfish often grow to over 14 feet long and weigh over 1,400 pounds. Due to this massive size, whole swordfish are not sold in neighborhood grocery stores, so the buyer must judge the quality of the fish based on the appearance of the steak.

Coloring is the most obvious indicator of the quality of a swordfish steak. The steaks will be mostly pink with some red streaks along the outside.

Fillets from a healthy swordfish will have a near translucent luminosity to them. Swordfish is nearly 30% fat, so under a light a steak will glisten.

There is a bloodline that runs down the length of the fish, that may appear unsightly but is perfectly safe to eat once properly cooked.

Most chefs or fish mongers in the United States will remove the bloodline before it ever reaches the customer.

However, any brown or green coloring is a sign that the fish is bad and should be discarded.

If a majority of the piece of fish looks like the bloodline, meaning the color is more red then it is pink, the fish should be discarded.

This is a sign that the fish was handled improperly in processing.

Raw Swordfish
Raw Swordfish.

What Texture Should Fresh Swordfish Have

A prized quality of Swordfish is its meaty texture which makes it ideal for many different cooking applications including grilling. To test if a piece of swordfish is good, one can press the steak or fillet gently.

It should feel somewhat firm to the touch and should have a fresh clean surface. The steak should be strong enough to hold together when put on a grill.

As any seafood begins to spoil it will develop slime on the surface. The more it spoils, the more slime will accumulate on the surface.

If the fish feels slimy to the touch or if slime is visible on the surface of the fish, it should be thrown away.

Purchasing Frozen Swordfish

If purchasing a frozen swordfish fillet, it should be completely frozen when purchased. If it is soft and does not feel completely frozen, make the proprietors aware of the problem and do not purchase the fish.

How to Thaw Frozen Swordfish

The best way to thaw frozen fish, is in the refrigerator with the steaks laid out flat for 24 hours. This is the safest way to defrost frozen fish and will ensure the best quality.

If time is of the essence, frozen fish can be thawed in a sink in a large bowl with cold or lukewarm water flowing over the fish.

If you are cooking a soup or a stew, the fish can be added to the dish frozen and defrosted as part of the cooking process, but this method should only be used as a last resort.

For an expensive piece of fish, like sword, I can only recommend using your microwave for thawing if you truly despise your dinner guests.

Fish should not be left in temperatures over 41°F for over four hours. Doing so allows for harmful bacteria to grow on the surface of the steak. Read more on thawing frozen foods here.

How Long Can Swordfish Stay In the Fridge after Thawing?

If thawed in the refrigerator under 41°F, fish can last 2 days. If another thawing method is used, the fish should be cooked the day it is thawed.

What Should Swordfish Smell Like?

Fresh swordfish should have a slightly salty smell like a cool ocean breeze. No seafood should smell foul or have any hint of ammonia smell.

Chefs and fish mongers alike will say that fresh fish should smell like the sea. To the unfamiliar all fish smells fishy, but there is a difference between the unpleasant “fishy” smell of spoiled fish and the pleasant breeziness of fresh seafood.

What Color Should Swordfish Be?

A swordfish fillet should be ivory pink throughout most of the fillet. If the color has turned brown, green or a flushed out white the fillet should be discarded.

Some of the muscles in the inner part of the fish near where the backbone was, can be dark red. These red muscles have a slightly stronger flavor to them then the whiter parts of the fillet.

Other than the slightly stronger flavor, these parts are safe to eat and are even prized by some swordfish lovers.

If a steak does not have the correct color of a healthy swordfish, don’t buy it or throw it out.

For further details on selecting high quality seafood that is safe to eat can be found here:

How Long Does Swordfish Last in the Fridge?

All seafood should be cooked or eaten within two days of the purchase date. Once cooked, swordfish can be stored for an additional three days if stored properly.

Following recommended methods for storing raw or cooked seafood will protect the diner from getting sick and the flavor of the fish.

How Long Does Uncooked Swordfish Keep In the Fridge?

It is impossible to tell how long that fish has been out of the water, so it is best to cook it on the same day it is purchased but if not, it can be stored up to two days.

Large piece of fresh frozen swordfish.
Frozen Swordfish

How Long Does Cooked Swordfish Last in the Fridge?

Any food that is intended for another day, should be chilled as quickly as possible after cooking and should not be allowed to sit at room temperature for more than four hours.

Food safety teachers call the temperature range from 70°F to 120°F the “Danger Zone.”

While a little melodramatic, it does emphasize the point that bacteria grow quickly in this temperature range.

Cooked swordfish should be chilled to under 70°F within four hours of cooking, then stored in an airtight container.

The Food and Drug Administration (FDA) recommends storing swordfish in your refrigerator at a temperature of 40°F or below.

Home refrigerator temperatures should be checked when storing fish or other temperature sensitive ingredients to protect the quality of those ingredients.

Alternatively, swordfish steaks or fillets can be stored on ice as long the fish is covered and not exposed to air.

Care should be taken when freezing swordfish to wrap the steaks tightly in plastic wrap and store them in zip top bags made for freezing.

Frozen fish will be safe to eat for up to 9 months after freezing, however the fresh quality of the fish will continue to decline the longer it is frozen.

For easy reference, check out this chart to see how long swordfish can last in each household setting:

SettingTemperatureLongevity RawLongevity Cooked
Outside76-90°F30 minutes (But not recommended)Outside
Countertop (Room Temperature)70°F1 Hour1 Hour
Countertop (High Temperature Holding Dish)135°FDo Not Hold Raw Fish at High Temperature4 Hours
Refrigerator32-40°F2 days3 days
Freezer0°F9 months3 Months

How to Cook Swordfish

The best way to cook swordfish is on the grill. Sword is one of the meatiest of all fish and a slight char from the grill adds to that meatiness.

A little olive oil, salt, pepper and a hot grill, served with fresh arugula, parmesan cheese shavings and a squeeze of lemon juice with a drizzle of olive oil and you have a wonderful summertime dinner.

For best results when grilling a swordfish steak, make sure the grill is clean and hot. Lightly oil the metal grills where the steak will be placed.

Rub oil on both sides of the steak and sprinkle salt and pepper generously on both sides.

Place the steak on the hot grill. The steak should sizzle. If it does not, let the grill heat up more.

Grill the steak for 2 minutes and 30 seconds. Carefully slide a metal spatula under the steak and rotate it 90 degrees and leave it for another 2 and a half minutes.

Then flip the steak over for 2 and a half minutes or until the steak feels like the part of your palm under the base of your thumb when you make a loose fist. It should give just a little but feel firmer than it did when it was raw.

If you have a meat thermometer, remove the steak when it reaches and internal temperature of 125 degrees.

Remove the steaks and let them rest for 4 minutes. The internal temperature will continue to rise to the FDA recommended 145 degrees while the steaks rest.

Swordfish has a versatile flavor and tastes just as good with soy sauce and rice as it does with fruit salsa or arugula and lemon juice.

How to Tell If Cooked Fish Is Bad?

Cooked fish should never taste bitter or sour on its own. Left over fish can have a pungent smell, but should not smell off, spoiled or sour. If the texture has broken down or there is any mold, the fish has gone bad.


Cooked food should not sit at room temperature for more than 4 hours. Most restaurants in the United States are required to discard any food that has not been chilled to below 40°F within 4 hours of cooking.

That is a good rule of thumb to follow at home as well. If I want to save cooked food, I will start chilling it within an hour of cooking it.

A grilled meal of Swordfish .
Grilled meal of Swordfish

Can Swordfish Make You Sick?

Consuming undercooked swordfish, or large amounts over long periods of time can cause illnesses. Pregnant women and young children should not consume swordfish due to its high levels of mercury.

Getting sick from food is called a foodborne illness. Foodborne illnesses can come from seafood like swordfish if it is not cooked or stored properly.

All seafood should be stored at 40°F or below until immediately before cooking. Swordfish should always be cooked to at an internal temperature of at least 145°F.

When cooking at home, it is important to clean and sanitize everything that touches the fish during the cooking process, including all knives, cutting boards, kitchen utensils and especially the thermometer.

What Happens If You Eat Fish That Has Gone Bad?

Reactions from eating bad or contaminated seafood very from upset stomach, diarrhea, vomiting, cramps, nausea, and fever.

Foodborne illness from undercooked seafood can begin to manifest symptoms as early as 4 hours from the time the seafood or as late as 7 days.

See the chart below from the FDA for a quick guide to signs and symptoms of possible foodborne illness.

OrganismCommon Name of IllnessOnset Time After IngestingSigns & SymptomsDurationFood Sources
Vibrio parahaemolyticusV. parahaemolyticus infection4-96 hoursWatery (occasionally bloody) diarrhea, abdominal cramps, nausea, vomiting, fever2-5 daysUndercooked or raw seafood, such as shellfish
Vibrio vulnificusV. vulnificus infection1-7 daysVomiting, diarrhea, abdominal pain, bloodborne infection. Fever, bleeding within the skin, ulcers requiring surgical removal. Can be fatal to persons with liver disease or weakened immune systems.2-8 daysUndercooked or raw seafood, such as shellfish (especially oysters)

For more information about food safety, the FDA recommends to call FDA’s Food Information Line at: 1-888-SAFEFOOD.

Swordfish Contains High Levels of Mercury

Swordfish is an apex predator, meaning that it survives by eating other, smaller fish. This means that mercury in these smaller fish is stored in the swordfish when the smaller fish get eaten.

When humans eat swordfish, the mercury transfers to the human and can linger for some time in hair and fingernails.

Mercury is a naturally occurring metal that can be toxic when consumed in large quantities or over long periods of time.

Individual affects very from person to person but can cause a number of symptoms including loss of motor skills, memory loss, trouble breathing and many more.

Qualified medical advice should be sought by anyone concerned about specific symptoms.

In a recent article on, Dr. Dan Brennan listed Swordfish as having the highest levels of mercury in a list of 12 tested seafood varieties.

Dr. Brennan wrote “It has an average mercury load measuring 0.995 ppm and highest loads measuring 3.22 ppm.”

Due to these high levels of mercury, many experts recommend that children and pregnant women not eat swordfish.

Final Thoughts

Swordfish is a high-quality fish, with a slightly sweet taste and meaty texture. Its firmness makes it ideal for multiple cooking applications, especially grilling.

With some commonsense precautions and a rudimentary knowledge of safe food handling, swordfish can be enjoyed by the vast majority of people.

Pregnant women and young children should not eat the fish, everyone else can enjoy it as an occasional treat without any fear.

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