How to know if tuna is spoiled

In this brief article, we will be having a look at some ways to tell spoiled tuna from tuna that is fresh and edible. We will also touch on some dangers of consuming spoiled tuna, as well as a few ways to handle and store tuna for the longest possible shelf life.

How to know if tuna is spoiled?

You will know when tuna is spoiled if you see any discoloration of brown, black, or even green in some cases can clue you in towards it being spoiled. The following signs will help you to determine is your tuna is spoiled or if it is still edible:

  • Color: Fresh tuna is pink, bright red, or light brown in color. If it appears dark brown, black, or even green, it has gone bad and is not fit for consumption anymore. Check the flesh close to the bone for an accurate assessment of its viability.
  • Smell: Even though tuna has a strong “fishy” scent, it is more of a meaty, saltwater-like scent. If your tuna smells foul and overpowering and makes you lose your appetite, it’s likely to have gone bad and should be thrown out immediately.
  • Expiration date: Check the bag or can your tuna come in. There should be a label on there telling you how much longer you can keep your tuna in the form of a “best by” or “use before” date. If the date has passed, get rid of the fish.
  • Condition of the bag/can: Check the can or the bag your fish came in before you open it. If it seems torn, bent, rusted, punctured, dented, or otherwise damaged, the fish inside is compromised and might already have gone bad.
  • Taste: If all else fails, try taking a small bite out of your tuna. If the taste feels off, do not consume that tuna, and immediately throw it out. This method is not recommended as it can expose you to spoiled tuna.

Can you get sick from eating spoiled tuna?

Yes, consuming spoiled tuna can lead to a range of foodborne illnesses, with symptoms that can vary in intensity from mild to severe (1-6).

You should be aware that spoiled tuna may contain harmful bacteria and toxins, such as Salmonella and Vibrio, which can cause foodborne illnesses and food poisoning (4). 

These bacteria can result in symptoms such as fever, vomiting, diarrhea, stomach pain, and potentially more serious complications for individuals who are more susceptible (7).

It is also important to be aware that even a small quantity of spoiled tuna can cause illness, and the severity of the sickness depends on the specific bacteria or toxins present in the fish. 

To safeguard your well-being, it is then crucial to never consume spoiled tuna and instead choose fresh fish that has been stored properly and obtained from reputable sources.

You should remember that proper storage and handling of fresh tuna, following appropriate food safety practices (8), are the best ways to prevent spoilage and reduce the risk of foodborne illnesses.

What should you do if you suspect you have eaten spoiled tuna?

If you consume spoiled tuna, you may quickly experience symptoms of food poisoning, typically appearing within 20 to 40 minutes after ingestion. These symptoms can include nausea, headache, dizziness, flushing of the face, and a rapid heartbeat (9).

If you notice any of these symptoms after eating tuna, it is advisable to promptly seek medical attention and consult with a doctor. A healthcare professional will assess your condition and provide appropriate treatment.

To alleviate symptoms caused by histamine poisoning from spoiled fish, antihistamines are commonly prescribed (10). In more severe cases, doctors may prescribe epinephrine and steroids to manage pronounced symptoms.

It is important to note that with proper medical care, most patients recover from scombroid poisoning within 3 to 4 days. In rare and severe cases, individuals may experience additional complications such as blurry vision or swelling of the tongue (11).

While the majority of cases of food poisoning from spoiled tuna are not life-threatening, it is always wise to consult a doctor if any concerning symptoms arise.

Remember that seeking prompt medical intervention can help relieve discomfort, manage complications, and ensure a speedy recovery.

How to store your tuna for the best possible shelf life?

Tuna can go bad very quickly if improperly stored, so it is important to handle and store it with care and under hygienic conditions. Here are a few ways for you to extend the shelf life of your tuna.

  1. Refrigerating: Tuna can last for up to five days in the fridge at the longest. To properly refrigerate, place in an airtight container at a relatively cold temperature. 

Having an airtight container is also important since the strong scent of tuna can linger on other items inside your fridge.

  1. Freezing: When frozen, freshly caught tuna can last up to two weeks. When freezing, it is best to place it inside a vacuum-sealed freezer bag to retain the greatest amount of flavor and freshness possible. 

Moreover, only thaw what you are immediately going to use since you will only have a few hours after you thaw the fish before it goes bad.

  1. Canning: Canned tuna is the most durable way of storing tuna since this method takes most of the moisture out of the fish, making it shelf-stable. Tuna can last for up to three years when canned.

Just make sure that you store your canned tuna in a cool, dark, and dry place, and elevated from the floor to best protect it from microbes. 

Keep an eye out for dents, dings, or rust on the cans since these can puncture the seal, making your tuna go bad a lot sooner than it would otherwise. The easiest place for this type of storage is your pantry.


In this brief article, we have had a look at some ways to tell spoiled tuna from tuna that is fresh and edible. We have also touched on some dangers of consuming spoiled tuna, as well as a few ways to handle and store tuna for the longest possible shelf life.


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