Does Freezing Fish Kill Bacteria? (Important Facts)

Does Freezing Fish Kill Bacteria

If you are wondering whether freezing kills bacteria in fish, then this post is for you.

I will share with you some facts about freezing fish that you might be interested in.

So, does freezing fish kill bacteria?

The answer is no, it does not. According to the FDA, freezing doesn’t kill all bacteria but will reduce their numbers and make them inactive. The good news is that even if you don’t freeze your food before storing it, there are other ways to prevent foodborne illness like cooking foods thoroughly and keeping raw meats separate from ready-to-eat foods.

Freezing will not kill all bacterial or parasitic organisms. Freezing has been proved to kill the pathogenic bacteria, like Salmonella and E-coli (Giardia Lamblia), that have been found in untreated water systems.

Still, freezing is useless when it comes to killing parasites such as tapeworms. Does this mean that freezing food is useless? No, it does not.

Freezing has few advantages over other preservation methods that should be considered.

So, what are the benefits of freezing fish?

1. Freezing keeps your fish from spoiling

Though freezing doesn’t kill all bacteria and parasites, it prevents the growth of bacteria and parasites that can cause food-borne illnesses.

Also, freezing maintains the quality and texture of fish and prolongs its shelf life.

2. Freezing prevents the loss of nutrients in fish

It prevents natural color changes, texture changes, flavor deterioration, fat oxidation, and water loss caused by enzyme actions.

Aging is a natural process that affects all foods and is caused by many factors such as light, heat, oxygen, and humidity.

Does freezing kill all the nutrients in fish? No, it does not.

Freezing only slows down the enzyme action resulting in slower changes to texture, color, and flavor of fish due to aging.

3. Freezing extends the fish’s shelf life

Freezing can prolong the storage life of fish for months.

The reason that you never see stale nor moldy fish in your local store is that they are constantly being introduced with new stocks and replaced as they expire.

Does this mean freezing can make food last forever? No, it does not. 

Freezing prolongs the storage life of fish but doesn’t stop the aging process.

Does freezing kill some parasites or bacteria in fish?

Yes, freezing kills some bacteria. But in most cases, it does not, especially if you are using a home freezer. It is not designed to reach below 0 degrees Fahrenheit.

Though freezing doesn’t kill all bacteria, it does prevent them from multiplying and spreading to other food in your freezer while keeping their nutrients and texture intact.

This makes frozen fish very convenient to use, compared to fresh fish that needs immediate cooking.

If you have a freezer at home, then freezing is one of the easiest ways to preserve fish and keep it longer than if you refrigerate it. 

Does Freezing Old Fish Make It Safe to Eat?

The fact that freezing prolongs fish’s shelf life doesn’t mean that you can use old fish.

It’s still best to consume fresh fish as soon as it is caught. But freezing has proven to be very effective in keeping your food fresh.


You shouldn’t consume any raw or undercooked fish before freezing for safety’s sake.

If you are not a big fan of eating raw fish but still want to take advantage of frozen fish for its nutritional value, then the following recommendations are helpful: 

The first is to make sure that it is flash frozen immediately after being caught or harvested. 

The second is to check the labeling to confirm that it was properly stored and handled to avoid bacterial growth.

How do you kill bacteria in raw fish?

Killing bacteria in raw fish involves several steps that you must do in order to kill off the harmful bacteria and preserve your fish as long as possible.

1. The first step is to remove as much blood from the raw fish as you can because fresh blood contains nitrate, which feeds microorganisms like bacteria.  Also, removing inedible parts such as scales reduces the number of bacteria in the body cavity and tissues.

2. The next step is to remove slime coating on fish by freezing it for few hours before cleaning it.

3. Clean your hands with soap and dampen your knife while preparing raw fish. Water activates enzymes that start decomposition so you want to keep as much moisture out of the fish as possible.

4. The last step is to cook the fish at high heat (60°C or more) to kill bacteria and prevent it from spreading to other foods in your freezer.

It’s best if you use a thermometer while cooking. Discard any leftover raw fish that is not immediately used for cooking. 

Remember, freezing only slows down the enzyme action and does not kill all bacteria.

Does freezing fish make it safe to eat raw?

If you are a big fan of eating freshly caught or harvested fish, then freezing is one of the best ways to preserve it so that you can eat it in the future. 

But just remember that freezing does not make fish safe to eat raw, it can only prolong shelf life and keep your food fresh for months.

Some bacteria are only gone dormant but not dead. This makes frozen raw fish unsafe when eaten raw.

Can you get salmonella from fish?

No, but… I’ve got more information on this topic for anyone who wants it.

Yes, and No, depending on your definition of “from.” There is a chance that you could get salmonella from fish if it was contaminated with bacteria prior to purchase.

However, there is no reason why you would acquire salmonellosis from eating raw fish.  What’s the difference?

The term “salmonella” encompasses a lot of types of bacteria: over 2200 to be exact.  For our purposes (discussing whether you can get salmonella from fish), we’ll be focusing on two types: Salmonella Typhi and  Salmonella Enteritidis.

Both are of concern when it comes to foodborne illness; however, only Salmonella Enteritidis has been shown to carry a certain type of bacteria capable of growing at cold temperatures. 

This is the case for one of the most common serotypes of Salmonella Enteritidis, S.Enteritidis PT4.

You can find two authoritative sources for research on this topic: The World Health Organization and the United States Department of Agriculture (USDA).

Both report that Salmonella Typhi is not at all associated with eating raw or undercooked fish.

Final Thoughts

In conclusion, the freezing process does not kill bacteria in fish but can slow down the growth of these dangerous microorganisms.

This is something that you need to think twice if you want to eat fish raw.

If you want to be safe, cooking is the safest way to go. This way you can kill bacteria in fish.


USDA: Food Safety and Inspection Service