The Serving Size for Fish

Fish is promoted for its beneficial effects on the heart, joints and brain, but the amount in a single serving can sometimes be confusing. Different organizations have differing definitions of fish serving size.

However, general recommendations of how much fish you should eat over the course of a week are fairly well-established. Your own health conditions can impact how much fish you should consume, so keep this in mind when calculating your own ideal serving size.

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A typical serving size of fish can range from 3 to 6 ounces, depending on the type of fish and its preparation. The American Heart Association considers 3.5 ounces of cooked fish, or about 3/4 cup, to be a single serving. A can of tuna contains about 5 ounces and lists 2 ounces, or 1/4 cup, as an appropriate single serving size on the nutrition label.

The American Dietetic Association food exchange lists, as described by the National Heart, Lung, and Blood Institute, calculate using 1-ounce servings of fish. Many restaurants and home cooks serve more than one serving's worth in a single meal. To estimate a single serving without weighing or measuring it, 3 ounces of fish is generally about the size of a woman's palm.

One ounce of fish contains approximately 35 calories and 1 gram of fat, placing it into the category of a very lean protein, according to the National Heart, Lung, and Blood Institute.

The American Heart Association recommends eating about two servings of fish per week, 6 or 7 ounces of fish, to reap the benefits of high levels of omega-3 fats. Most people should try to keep fish consumption under 12 ounces per week, or about three to four servings, to avoid mercury contamination.

A single serving of shark, swordfish, tilefish, and king mackerel has unhealthy levels of mercury, according to the Cleveland Clinic. Pregnant or lactating adults and young children should avoid consuming even a small amount of these fish and limit their two weekly servings to low-mercury fish such as salmon, catfish, pollock and canned light tuna.

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Some people should get extra servings of fish each week. People with heart disease should aim to get 1 gram or more of the fish-derived omega-3 fats EPA and DHA every day, and people with high triglycerides might need as much as 4 grams per day, according to the Cleveland Clinic. EPA supports cells growth and division, blood clotting, muscle function and digestion, while DHA supports brain health.

Individuals who want to get the benefits of fish but eat fewer than the recommended servings per week might consider taking a fish oil supplement.

According to the National Institutes of Health Office of Dietary Supplements, omega-3 fatty acids reduce overall death rates, from any cause. They also help prevent specific cardiovascular conditions including sudden death, heart attack and death of heart tissue. Fish oils can also help lower blood sugar levels and reduce joint pain associated with rheumatoid arthritis.