Getting enough protein as a pescatarian -- a person who eats fish but no other animal meat -- is generally an easy task, since pescatarians eat fish and shellfish, both excellent protein sources. If you follow a pescatarian diet, beef, poultry and pork are off your diet menu. Some pescatarians eat eggs and dairy foods, while others do not.
Adult men need around 56 grams of protein per day, while women need around 46 grams, reports the Centers for Disease Control and Prevention. Protein contains amino acids, which are necessary for building new tissue and repairing tissues that break down continuously from wear and tear. Not all protein sources contain the 20 essential amino acids; proteins that do, such as animal flesh, fish, eggs and dairy products, are called complete or high-quality proteins. Your body doesn't store protein, so you need to get your daily quota every day.
Protein in Fish
The amount of protein in different varieties of fish and shellfish varies. Fattier fish contain less protein than lean fish, but often supply healthy omega-3 fatty acids. The protein in fish is highly digestible because it contains less connective tissue than animal flesh; this is also why fish flesh flakes so easily. The flakiness of fish makes it an ideal protein for the elderly, who might have trouble chewing other types of meat. Most fish provide around 22 grams of protein per 3.5-ounce serving. Tilapia, for example, provides 19.7 grams per serving, while yellow-fin tuna adds 23.3 grams of protein per 3.5-ounce portion.
Protein in Shellfish
Shellfish contains slightly less protein per 3.5-ounce serving. Shrimp supplies 18 grams, for example, while oysters offer just 13 grams. Littleneck clams fall on the low side of the protein scale, with just 7.6 grams per 3.5-ounce serving, while blue crab, with 20 grams, and lobster, with 17 grams per portion, come close to fin fish. If you like calamari, a serving will supply 15.5 grams of protein.
Other Protein Sources
While fish serves as a good source of protein, it's not the only source of protein in a pescatarian diet. If you eat eggs and dairy, both supply protein. Nuts, seeds and legumes also add a hefty dose of protein to the pescatarian diet. While these are incomplete proteins, containing some but not all essential amino acids, they supply antioxidants, healthy fats and vitamins and minerals, including some not found in fish.