Does Canned Tuna Go Bad: 9 Tell-Tale Signs of Bad Canned Tuna

Canned tuna is a staple food that deserves its place in everyone’s pantry. It can be used in a number of dishes and it has an excellent shelf life thanks to the sturdy packaging.

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Canned foods are inexpensive, easy to store, and are excellent backup foods. This canned food (canned meat) is great for tuna salad and tuna fish sandwiches. It lasts longer than fresh tuna and spoilage is limited with unopened canned tuna.

While the shelf life is longer for canned foods, including tuna, there still is an expiration date on the can to abide by.

However, we all have a horror story of how an incorrect expiration date traumatized us and put us off eating the food ever again. Bad canned tuna can make you sick and we're not talking about mercury poisoning. Raw fish itself needs to be handled with care. Canned fish can be handled a little differently. Tinned tuna can cause food poisoning if handled inappropriately.

9 Ways To Tell If Your Canned Tuna Is Bad

No one wants to be put off eating tuna fish again, which is why we’re here to protect you from the worry of wrong expiration dates. Today we’ll be looking at nine ways to tell if your canned tuna has gone bad. 

If you read our article and find that your canned tuna is displaying signs that it might be off, you should throw it in the trash right away. You can get ill from consuming bad tuna, so don’t risk your health for some tuna fish.

Checking the expiration date

Canned tuna has a much longer shelf life than tuna fish outside of a can. It might surprise you to know that tuna can be stored within a sealed can for up to three to five years!

This is an amazing length of time that surprises many people when they first realize how long the tuna might have been kicking about in the can. 

Your canned tuna usually has an expiration date printed on the can which tells you how long the food is good for. The date is normally considered a ‘best by’ date, meaning that you should consume it before this date. 

While the tuna might be still edible after this date, the manufacturer cannot take responsibility for it if it goes bad as it’s past the expiration date.

If you’ve found a can of tuna in the back of your pantry past its expiration date that you’re not sure about the freshness of, keep reading to find out. 

Ways to tell if your canned tuna is bad

1. Read the can

The easiest way to tell if your canned tuna is still good is to read the expiration date on the can.

The longer the date has been passed, the more likely it is that your tuna fish will be bad. If you’re worried about your tuna going bad, make sure to eat the food before this date has surpassed. 

Some people do not want to open a can that contains bad tuna fish. If you’re particularly worried about this, we would recommend not letting it get to this point.

However, if you’ve found a can that you’ve forgotten about and want to know if it’s still good, you should check the date first. 

If the date has surpassed and you’re already skeptical about the quality of the tuna inside of the can, use the rest of the tips below to tell you whether you should throw the can out or whether it’s still good to eat. 

2. A fishy smell

It’s no secret that fish doesn’t always smell the best, particularly if it’s been left in a can for who knows how long! One of the easiest ways to tell if your fish is bad is to brace yourself and open the can. 

Once you’ve popped the lid, you might get an overpowering smell of fish, oil, and salt. If you are a regular canned tuna user, you should know the smell that we’re referring to here.

However, if you open the can and the smell is altered you might have a can of bad tuna on your hands. 

The smell we’re referring to here is an acidic smell. The can won’t smell of normal tuna fish if it’s gone bad, but rather it will smell ‘off’. If you notice a smell like this you might want to take precautions and throw the can right out. 

Wash your hands thoroughly and disinfect anywhere that the tuna brine might have splashed while you were opening the can. This will ensure that there is no spoiled fish around you. 

3. Leaking liquids

A leaking can indicates that the tuna fish has not been preserved in the correct way, so you should throw your tuna out right away.

If there is a leak, it means that the meat has not been kept properly and therefore is not guaranteed to be safe to eat. 

Canned foods are pressure sealed to promote freshness. If the can is leaking or has been popped, this freshness has been compromised.

Even if the meat looks fine and smells fine, we recommend that you don’t risk it and just throw it straight into the trash. 

4. Corroded metal

Your canned tuna will be residing in a metal can. While metal is a relatively strong and durable material, it is still not invincible.

Metal can rust and become corroded if it’s not stored correctly, which might make your tuna go bad quicker than it should. 

Rust and corrosion can make tiny holes in the metal can which might affect the preserving process.

Moisture and air will be able to get into the can and affect the quality of the tuna fish. If there are any signs of corrosion or rust on your can, you might want to throw it out. 

5. The color

Tuna fish is normally a pinky, light brown color when it’s fresh in the can. Checking the color before you eat your canned tuna can assure you that your food is still good to eat.

However, do not eat your tuna if there are any spots of discoloration. 

These could be dark brown, green, or black. Discolored tuna is definitely not safe to eat so you shouldn’t even think about it. If you’re not used to using canned tuna and don’t know the usual color that it should be, err on the side of caution. 

Use the other ways that we’ve mentioned to see if your canned tuna seems bad. If you’re worried about the suspicious color and the can is showing more signs that it’s gone bad, throw the tuna fish away. 

6. The color - continued 

We want to reiterate that the color of your tuna is very important. Some tuna looks brown in the can and is still safe to eat. But we just said that dark brown tuna is not safe to eat? We know, and here is where it gets a little trickier. 

Brown tuna is still edible when the brown pieces are warm brown in color. In other words, the tuna will have a reddish hue while still being brown. If the tuna is dark brown with cool undertones, the tuna should not be eaten. 

We like to think of it as if the fish is red and looks ‘alive’, it’s fine to eat. However, if the fish is grey and lifeless you shouldn’t eat it. Make sure you’re only eating tuna with red undertones rather than grey ones. 

7. Explosion!

We bet that you didn’t know that cans could explode when they’re in your pantry just minding their own business, did you? While this is very uncommon, it still can happen and is a sure sign that something is wrong with the canned tuna. 

However, as the tuna is probably all over your pantry thanks to the exploding can, you might not be able to eat any of it anyway. Simply clean up and throw all of the tuna away, making sure that you disinfect everywhere that the fish touched. 

A can of tuna can also explode when you pop the can yourself. The tuna might shoot out of the opening thanks to the pressure. This can show you that the can was defective and not preserving the tuna correctly. 

If the tuna can explodes, just throw it all away and start again with a new can. The can might also be bulging from the top or bottom. If the can looks like it’s going to explode or does explode once you open it, get rid of the fish. 

8. The quality of the can

As you can see, the can is very important when you’re checking the quality of your tuna fish.

You should also look for dents in the can as these can adjust the expiration date significantly. Dents are not always sinister, but it’s sometimes worth checking the dents beforehand. 

Dents in the lid of your canned tuna are the worst to find, so be particularly cautious of these. The dent might indicate that the pressurization within the can has been altered, affecting the preservation of the tuna fish. 

Many people don’t know it, but dents in the lids of canned tuna can promote the growth of salmonella and other unwanted bacteria.

So, we highly recommend only using canned tuna with pristine cans that have no dents or damage to them. 

9. Take a bite

No, we’re serious -  the easiest way to see whether your tuna fish is good or bad is to take a small bite and see how it tastes. Taking a small bite of bad tuna shouldn’t harm you, so this is safe to do so. 

If the tuna has an ‘off’ taste or tastes acidic, spit it out straight away and throw the fish out. We would never risk eating something that doesn’t taste how it would normally, especially if it’s past the expiration date.

Storing canned tuna properly

To avoid your canned tuna going bad, you should store it away from sunlight and heat.

A kitchen cupboard or pantry would be ideal for your tuna. Make sure that the cans are stored somewhere that they cannot fall and become compromised. 

Keep the cans dry as well to avoid corrosion from forming on the cans. We would also recommend keeping them somewhere that you’re not going to forget about them. Eat them before the expiration date and you won’t have to worry about whether the meat is bad or not. 

We know that it can be tempting when you find a sweet deal at the grocery store on multiple cans of tuna for a low price. What’s the harm in stocking up? You ask, before taking them home and forgetting about them almost instantly. 

Only store as much tuna as you need to prevent you from missing the expiration dates. While hoarding canned goods sounds good in theory, you might just end up wasting all of your money for nothing. 

Once you open a can of tuna fish, you should remove the leftover tuna from the can and place it in a bowl. Cover the bowl with plastic wrap and store it in the refrigerator. Canned tuna should only be left in the refrigerator for up to 24 hours. 

Leaving it for any longer might cause it to go bad before you can use it all up. Some people like to err on the side of caution and throw out any tuna that they don’t use right away. It’s up to you whether you want to use it within the next day or not. 


We hope that you’ve found some useful information within our article today. Canned foods are usually safe to eat long after they’ve been canned due to the preservation process that the can creates.

However, you should always put your health first and ensure that your tuna is edible. 

There are a few distinctive ways to ensure that your tuna is good before you eat it. Firstly, check the date and see if there are any distinct issues with the can.

Rust, dents, and holes are telltale signs that your tuna might not be good to eat anymore. 

Once you open the can, the smell, color, and taste of the tuna will be able to tell you whether you can use the meat or not. When in doubt, throw it out. A possibly bad can of tuna is not worth risking your health for. 

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Cassie brings decades of experience to the Kitchen Community. She is a noted chef and avid gardener. Her new book "Healthy Eating Through the Garden" will be released shortly. When not writing or speaking about food and gardens Cassie can be found puttering around farmer's markets and greenhouses looking for the next great idea.
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