Flounder are large, flat fish found on the bottom of saltwater locations around the United States. A type of white fish, they contain very little fat and no carbohydrates. Instead, flounder is relatively protein-rich and contains some beneficial minerals. Though an 8 oz. serving of fish is a fairly large portion, this amount provides rather low levels of nutrition. Flounder contains over 80 percent water, reducing the overall nutritional content of the fish.
An 8 oz. piece of cooked flounder contains 183 calories, according to the USDA National Nutrient Database. That makes it a relatively low-energy food per serving. The average 175 lb. moderately active man needs around 2,800 calories per day, and the average 125 lb. woman 2,000 calories. An 8 oz. serving of flounder makes up only 6.5 percent of an average man's daily calorie intake and 9 percent of a woman's.
Protein and Fat
Aside from water, protein is the most abundant substance in flounder. An 8 oz. piece delivers over 32 g of protein. Flounder protein is classed as "complete"; it contains the full range of essential amino acids, with leucine and lysine found in the highest doses. Flounder is also a very lean source of protein. The fish contains just 5 g of fat per 8 oz., or under 2 percent fat. Only 1.2 g of this is saturated fat, a type linked with poor heart health.
Vitamins and Minerals
Flounder contains a range of minerals and vitamins, many in small amounts. The fish has no vitamin C and low levels of calcium and iron -- three important dietary substances. However, some flounder contains fairly high levels of sodium, as much as 771 mg per 8 oz. That's almost a third of your recommended 2,300 mg maximum per day. To boost the vitamin C, iron and calcium content of a meal involving flounder, try serving the fish with low-fat cream sauce and spinach. The addition of dairy and dark green vegetables increases the calcium, iron and vitamin C.
Flounder contains lower amounts of fish oils -- and, hence, less omega-3 fatty acid -- than some other fish do, such as salmon and mackerel. For example, an 8 oz. serving of cooked mackerel contains a total of 2.7 g of the three important omega-3 fatty acids EPA, DPA and DHA. The same serving of flounder offers only 0.8 g of the same fatty acids. These substances may help lower the amount of cholesterol in the blood and help keep your heart and circulation system in good condition.