Canned or tinned fish are food fish which have been processed, sealed in an airtight container such as a sealed tin can, and subjected to heat. Canning is a method of preserving food, and provides a typical shelf life ranging from one to five years.

Fish have low acidity levels at which microbes can flourish. From a public safety point of view, foods with low acidity (pH greater than 4.6) need sterilization at high temperatures (116–130°C). Achieving temperatures above the boiling point requires pressurized cooking. After sterilization, the containing can prevents microorganisms from entering and proliferating inside. Other than sterilization, no other method is dependable as a preservative. For example, the microorganism Clostridium botulinum (which causes botulism) can only be eliminated at temperatures above the boiling point.

Preservation techniques are needed to prevent fish spoilage and lengthen shelf life. They are designed to inhibit the activity of spoilage bacteria and the metabolic changes leading to a loss of fish quality. Spoilage bacteria are the specific bacteria that produce the unpleasant odours and flavours associated with spoiled fish.

Canned fish is a convenient way to bring the catch of the day to meals and packs in many nutrients in a small can. While canned tuna is likely the most well-known canned fish, there are other nutritious options that may be available in your State, like canned salmon, mackerel, and sardines.

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Canned fish is loaded with nutrients; it is protein-dense and provides beneficial omega-3 and omega-6 fatty acids. Canned fatty fish, like tuna, salmon, mackerel, and sardines are also a source of vitamin D, vitamin B12, choline, iron, and iodine. Canned sardines and salmon with the bones provide calcium. 

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Rinse sodium-containing canned foods, such as beans, tuna, and vegetables before eating. This removes some of the sodium.

Canned fish is often packed in oil or water. Canned fish packed in oil is higher in beneficial fats and provides more energy, or calories per serving.

It is recommended that pregnant and breastfeeding adults eat two to three servings a week of fish that are lower in mercury, which includes canned salmon, canned light tuna, canned sardines, canned Atlantic mackerel, or Pacific chub mackerel.

Single serving: 1 ounce of fish is considered to be a 1-ounce equivalent serving of protein. 1 ounce of canned tuna, salmon, mackerel, or sardines contains over 5 grams of protein. A serving size of canned fish is 4 ounces, or the size of an adult palm.

Storage: Canned fish can be stored for 3-4 days in the fridge in an airtight container once opened. An unopened can of fish can last up to 3 years in the pantry, but also make sure to check the “Best if Used By” date on the packaging.

Preparing: Canned fish is ready to be eaten right out of the container! See below for ideas on how to use canned fish, along with recipes. Canned fish is often packed in oil or water, which can be drained depending on recipe directions or preferences.

Uses: Canned fish has a variety of uses. Canned tuna is classically used in tuna salad and in tuna melt sandwiches. Canned fish can also be used creatively in pasta dishes to pack in the protein. Tuna and salmon burgers or fish cakes are an additional delicious use of canned fish. Sardines can be added to toast, salad, pizza, and more. Squeeze some lemon on sardines or mackerel for added flavor. Swap canned salmon or mackerel into a tuna recipe for something a little different!

Raw fish and shellfish should be kept in the refrigerator (40 °F/4.4 °C or less) only 1 or 2 days before cooking or freezing. After cooking, store seafood in the refrigerator 3 to 4 days. Any frozen fish or shellfish will be safe indefinitely; however, the flavor and texture will lessen after lengthy storage. For best quality, freeze (0 °F / -17.8 °C or less) cooked fish for up to 3 months. Frozen raw fish is best used within 3 to 8 months; shellfish, 3 to 12 months. Seafood should never be left out over two hours.

You can store commercially canned fish, such as tuna, for up to five years in the pantry; home canned fish, only one year. 

FDA and EPA have issued advice regarding eating fish.

This advice can help those who might become or are pregnant or breastfeeding as well as parents and caregivers who are feeding children make informed choices when it comes to the types of fish that are nutritious and safe to eat.

Fish provide key nutrients that support a child’s brain development.

Fish are part of a healthy eating pattern and provide key nutrients during pregnancy, breastfeeding, and/or early childhood to support a child’s brain development:

• Omega-3 (called DHA and EPA) and omega-6 fats
• Iron
• Iodine (during pregnancy)
• Choline

Choline also supports development of the baby’s spinal cord. Fish provide iron and zinc to support children’s immune systems. Fish are a source of other nutrients like protein, vitamin B12, vitamin D, and selenium too.

Eating fish can provide other health benefits too.

Fish intake during pregnancy is recommended because moderate scientific evidence shows it can help your baby’s cognitive development.

Strong evidence shows that eating fish, as part of a healthy eating pattern, may have heart health benefits.

Healthy eating patterns that include fish may have other benefits too. Moderate scientific evidence shows that eating patterns relatively higher in fish but also in other foods, including vegetables, fruits, legumes, whole grains, low- or non-fat dairy, lean meats and poultry, nuts, and unsaturated vegetable oils, and lower in red and processed meats, sugar-sweetened foods and beverages, and refined grains are associated with:

• Promotion of bone health – decreases the risk for hip fractures
• Decreases in the risk of becoming overweight or obese
• Decreases in the risk for colon and rectal cancers

A healthy eating pattern consists of choices across all food groups (vegetables, fruits, grains, dairy, and protein foods, which includes fish), eaten in recommended amounts, and within calorie needs. Healthy eating patterns include foods that provide vitamins, minerals, and other health-promoting components and have no or little added sugars, saturated fat, and sodium.

The Dietary Guidelines for Americans recommends eating fish as part of a healthy eating pattern.

The Dietary Guidelines for Americans recommends:

• At least 8 ounces of seafood (less for children) per week based on a 2,000 calorie diet.
• Those who are pregnant or breastfeeding consume between 8 and 12 ounces per week of a variety of seafood from choices that are lower in mercury.

Choose a variety of fish that are lower in mercury.

While it is important to limit mercury in the diets of those who are pregnant or breastfeeding and children, many types of fish are both nutritious and lower in mercury.

This chart can help you choose which fish to eat, and how often to eat them, based on their mercury levels.

What is a serving? As a guide, use the palm of your hand.

Pregnancy and breastfeeding:

• 1 serving is 4 ounces

Eat 2 to 3 servings a week from the "Best Choices" list
(OR 1 serving from the "Good Choices" list).

Childhood:
On average, a serving is about:

• 1 ounce at age 1 to 3
• 2 ounces at age 4 to 7
• 3 ounces at age 8 to 10
• 4 ounces at age 11

Eat 2 servings a week from the “Best Choices” list.

Store commercially canned foods and other shelf stable products in a cool, dry place. Never put them above the stove, under the sink, in a damp garage or basement, or any place exposed to high or low temperature extremes. High acid foods such as tomatoes and other fruit will keep their best quality up to 18 months; low acid foods such as meat and vegetables, 2 to 5 years. If  cans are in good condition (no dents, swelling, or rust)  and have been stored in a cool, clean, dry place they are safe indefinitely. While extremely rare, a toxin produced by Clostridium botulinum is the worst danger in canned goods.

NEVER USE food from containers that show possible "botulism" warnings: leaking, bulging, or badly dented cans; cracked jars or jars with loose or bulging lids; canned food with a foul odor; or any container that spurts liquid when opening. Even a minuscule amount of botulinum toxin can be deadly. Can linings might discolor or corrode when metal reacts with high-acid foods such as tomatoes or pineapple. As long as the can is in good shape, the contents should be safe to eat, although the taste, texture and nutritional value of the food can diminish over time. Home canned foods should be used within 1 year.

For a healthy heart, the American Heart Association and the Dietary Guidelines for Americans recommends eating two, 3.5 oz servings of fish per week. Questions like "Why? Which fish?" immediately come to mind. Also, "Should I be concerned about mercury? Is wild-caught fish better than farmed?"

Why eat fish? Several studies have shown that eating fish reduces risk of heart disease. Fish is an excellent source of protein and many species are also rich in omega-3 fatty acids, particularly the long chain omega-3's EPA and DHA. Consuming these long chain omega 3's reduces blood clots, triglycerides and arrhythmias (irregular heartbeats). Eating at least 250 mg of these omega 3's per day is enough to provide health benefits. Unfortunately, Americans eat less than half of this amount.

But which fish should I eat? Does it matter how I cook it? For a heart-healthy effect, guidelines recommend eating "fatty" or "oily" fish. These terms are misleading, as most of the fish we eat are fairly lean. "Oily" fish like tuna and salmon are typically high in EPA and DHA--lower amounts of which are found in trout, sardines, walleye, oysters, shrimp and mussels. Americans consume about 4 lbs of shrimp and 2 lbs tuna and salmon per person each year. Baking or grilling is recommended instead of frying.

A common concern about eating fish, especially for pregnant and nursing mothers, is mercury. Mercury is a fat-soluble element that can accumulate particularly in older, large predatory fish like shark, swordfish, king mackerel and tilefish. The US Environmental Protection Agency and the Food and Drug Administration recommend that women who may become pregnant or are pregnant or nursing, as well as young children limit their intakes to 12 ounces of such fish as canned tuna or salmon, and should avoid species such as shark and king mackerel. This limit is well above the two, 3.5 oz servings per week for heart benefits.

As the world's population grows, the demand for fish is increasing. Already, 90 percent of the global wild fish stocks are rated as fully or over-exploited. For this reason, fish farming, which started in the US in the 1800's, is an increasingly important source of Atlantic salmon. Farmed in cold water currents, over 1.5 million tons of Atlantic salmon are produced yearly from Norway, Chile, the United States and Canada. Shrimp, oyster, and mussels, and non-marine fish like rainbow trout and catfish are also extensively produced by such aquaculture methods.