How To Tell If Canned Tuna Is Bad? – Learn 7 Prominent Tricks

Written by Patricia Jones

Ideal storing of fresh or canned fish is the first step in keeping them safe to eat. It is a misfortune if your purchased items go bad or get spoiled.

At this point of time, you have to throw them into the trash. In case, you consume decayed fish to save your money. It may cause foodborne illness due to seafood poisoning.

This is the reason why I’ve come up with this article on how to tell if canned tuna is bad. A thorough read of the entire post will ensure that there will be no issues.

If we consider canned tunas go bad and become unsafe to eat, it is not only a loss of your hard-earned money but also a loss of food.

Considering the loss of food items in the US, it costs around $200 per month. For more details, you can check a separate article on how to preserve food.

Before moving on to the tricks of determining bad canned tuna, let’s know some interesting facts about the said fish-

What Is Tuna? – A Fish With Sleek And Streamlined Body

It is a fish that can maintain its body temperature higher than surrounding water. It is capable of attaining a speed up to 75 km/h under water.

Canned tunas are quite popular in many countries. It is stored in cans by dropping them in oil or water. It is rich in omega-3 fatty acid and a good source of protein.

Apart from this, it is a source of vitamin A, vitamin D, calcium, magnesium, iron, potassium, phosphorous and a trace of other minerals.

If we consider its nutritional value per 100g weight, it provides up to 200 kcal energy. In the US, tuna fish is one of the common dishes found in the dining table.

Let’s back to the main topic how to tell if tuna is bad for eating or not-

How To Tell If Canned Tuna Is Bad? – Check Out The Tricks Here

It’s not a challenging task to find whether your food is safe to eat or you need to look for its alternatives. With my years of experience as a chef, I’m going to provide you with 7 helpful ways that can make you choose healthy food.

1.Can Explodes When Opened

In certain cases, it has been observed that users have to face the challenge of sudden projecting out of food when the can is opened.

You may also find that it produces a sound of an explosion. It notifies that your canned tuna is no more in good condition.

Without creating any mess out of it, you must throw the container into the trash.

2.Corrosion Of Can

When the canned tuna is stored for a long time, it starts to corrode. Over the course of time, it also creates holes on the surface.

From these small holes, it lets air and moisture enter the food. Eventually, it develops bacteria that lead to the spoilage of food items.

It is advised not to use such canned tunas. It is better to throw corrode can into the dustbin.

3.Expired Sell-By-Date

If the stored canned item crossed the ‘sell-by’ or ‘best-before’ date, it is not safe to eat. In case, you have kept it in the freezer. It may remain good for a few more months.

Or else, it is recommended to throw this spoiled tuna without opening the can. If you have a query on ‘how to know if canned tuna is bad by checking its sell-by-date’, it is solved by now.

4.Dents On The Can Surface

A dent on the can surface can lose the air-tight seal and allow moisture to enter food. It helps in the growth of bacteria and spoils the food item.

Over time, you may also notice a pungent smell coming out of the box. In this situation, it is better not to use tuna and look for its alternatives.

Suppose you come across such canned tunas on the supermarket. Needless to say, pick the one that looks perfect from outside and also ensures its sell-by date.

5.Leaking Of Food Items

It is not among the most common problems but leakage can happen. While purchasing a canned tuna, you may find water or oil is leaking out from the container.

So, it is wise to look for other cans skipping that leaked one. However, this can also happen with your stored containers.

It is advised to check the surface of the tin before breaking its seal. This ensures that you are going to eat good quality food.

6.Acrid Smell Out Of The Can

Suppose any of the above-mentioned points haven’t been matched and you have opened the container. The smell of the food can define whether it is safe to eat or you have to discard it.

If the food starts spoiling or already spoiled, you observe acrid smell out of the can. It is because of the acidic or chemical reaction of food.

Throw the container straight into the trash and wash your hand thoroughly.

7.Unnatural Color Of The Food

Fresh and good quality tuna looks bright red to light pink in color. By adding preservatives, it turns to become visually brown shade.

If the canned tunas go bad, you can see dark brown steaks or black color of food. Depending on the additives, it may also turn green in color. So, it is unsafe to eat.

At this point of time, you must discard the entire can and throw it into the trash.


In case, you want to know how to tell if tuna is fresh and safe to eat.

It should have a sea-air smell without producing over fishy odor. You may also come across a dark meaty strip running through the body of the tuna fish.

What Does Tuna Look Like? – Always Eat Fresh Food

It has two dorsal fins on its back. At its end, you can notice 7 – 10 yellow finlets that run to the tail. The dorsal side looks metallic dark blue that transforms into silvery to whitish underside.

But you won’t find similar shape and color of canned tunas. This is because canned food is made from tuna’s meat. Now, water or oil is poured into the can with tuna before sealing it.

The flesh of tuna can have a range of colors from light pink to reddish brown. Actually, it depends on the variety of tuna (species) that defines the color.

Raw tuna steaks are much like raw beef cuts in its color. This tells that it is fresh and safe to eat.

How To Store Tuna? – Additional Information

Canned tuna can be refrigerated in the home kitchen. If it remains unopened, you can make its best use up to 1 year. If it is frozen, you can extend its lifespan to a great extent.

In case, you want to store the leftovers after opening a can. It is advised to vacuum seal the can properly and place it in the refrigerator. It may remain good for the next 3 days.

If you freeze opened can of tuna after sealing the same, it may last for up to 7 days.

For vacuum sealing the opened cans, you can check this article and know how to make the process fast and convenient.


Consumption of tuna fish helps in improving the immune system. It also strengthens your bone and protects against injuries like fracture. It is also good for skin.

Bottom Line

I hope you understand how to tell if canned tuna is bad or not. In fact, you can help your family and friends if they come across similar kind of situation.

Just be sure your stored food still remains at its peak quality before eating and stay healthy!

For any query or suggestion, you are free to comment on the below box. If you found this post helpful, you must share your thoughts.

Eat Healthily! Stay Fit!

About the author

Patricia Jones

Patricia is a fine dining chef at Wake Forest, North Carolina. She is also a caring mom and a lovely sister. Her heart and passion lies in the art of cooking great dishes for her family and customers.

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