A pescatarian is someone who eats fish and shellfish but no other meat or poultry. The diet is primarily plant-based, built around vegetables, fruits, grains, legumes, nuts, and seeds, with eggs and dairy typically included alongside seafood. Think of it as vegetarian plus fish.
What Pescatarians Eat and Don’t Eat
The simplest way to understand the diet: take everything a vegetarian eats, then add fish and shellfish. That means fruits, vegetables, whole grains, beans, lentils, nuts, seeds, eggs, and dairy are all on the table. Chicken, beef, pork, lamb, turkey, and any other land-animal meat are not.
On the seafood side, everything counts. Salmon, shrimp, cod, sardines, tuna, crab, oysters, mussels, squid, lobster, scallops, and any other fish or shellfish are all fair game. There are no strict rules about how often you need to eat seafood. Some pescatarians have fish daily, others just a few times a week, filling the rest of their meals with plant proteins like lentils, chickpeas, and tofu.
Heart and Metabolic Health Benefits
The strongest evidence for the pescatarian diet involves heart health. A large UK Biobank study found that fish eaters, compared to regular meat eaters, had a 21% lower risk of ischemic heart disease, a 30% lower risk of heart attack, a 21% lower risk of stroke, and a 22% lower risk of heart failure. These numbers held after adjusting for other lifestyle factors like smoking and exercise.
The benefits likely come from two directions at once. You’re adding omega-3 fatty acids from fish, which reduce inflammation and support healthy blood vessels. And you’re removing red and processed meats, which are linked to higher cardiovascular risk. Research on vegetarian-style diets, including pescatarian patterns, also shows a reduced prevalence of type 2 diabetes, though the degree of protection varies depending on overall diet quality.
The Omega-3 Advantage
Omega-3 fatty acids are the flagship nutrient of this diet. Your body can’t produce them efficiently on its own, and the forms found in fish (EPA and DHA) are far more usable than the plant-based form found in flaxseed or walnuts. These fats support brain function, reduce inflammation, and play a role in heart rhythm stability.
Not all fish deliver the same amount. Fatty, oily fish are the richest sources. Per 100 grams of fish, Atlantic mackerel provides about 2.5 grams of combined EPA and DHA. Farmed Atlantic salmon delivers around 1.8 grams. Sardines and herring each offer roughly 1.0 to 1.1 grams. By contrast, leaner white fish like cod, flounder, and haddock contain only about 0.2 grams per serving. They’re still nutritious, just not omega-3 powerhouses.
A practical approach is to eat fatty fish two or three times a week and fill in with leaner fish, shellfish, or plant-based meals on other days.
Mercury: Which Fish to Limit
Mercury accumulates in fish tissue over time, so larger, longer-lived predator fish carry the highest concentrations. The FDA flags seven species to avoid entirely if you’re pregnant, breastfeeding, or feeding young children: king mackerel, marlin, orange roughy, shark, swordfish, Gulf of Mexico tilefish, and bigeye tuna. For everyone else, these should be eaten only rarely.
The “best choices” list is long and reassuring. Salmon, sardines, shrimp, cod, catfish, anchovies, pollock, tilapia, trout, scallops, oysters, clams, crab, and lobster all fall in the lowest-mercury category. The FDA recommends two to three servings per week from this list (a serving is about 4 ounces cooked). Smaller fish and shellfish like anchovies, mussels, and scallops tend to have the lowest mercury levels of all.
Nutrients to Watch
Because pescatarians eat fish, eggs, and dairy, they avoid most of the nutritional gaps that challenge vegans. Vitamin B12, which is absent from plant foods, is plentiful in fish, shellfish, eggs, and dairy. Protein is rarely a concern when seafood, legumes, eggs, and dairy are all in rotation.
Iron is the main nutrient to keep an eye on. Red meat is the most concentrated dietary source of easily absorbed iron, and without it, some pescatarians (especially women of reproductive age) can fall short. A study of people following plant-based and pescatarian diets in Norway found that 8% of women had iron levels below the reference range. The risk is manageable: pairing iron-rich plant foods like lentils, spinach, and fortified cereals with vitamin C (from citrus, peppers, or tomatoes) significantly improves absorption. Shellfish like clams and oysters are also excellent iron sources. If you’re a woman with heavy periods, periodic blood work to check iron stores is a reasonable precaution.
Environmental Footprint
Switching from a meat-heavy diet to a pescatarian one roughly cuts your food-related carbon emissions in half. Research from Oxford University found that meat-rich diets (more than 100 grams of meat per day) produced around 7.2 kg of carbon emissions daily. Fish-eating diets produced about 3.8 kg, nearly identical to vegetarian diets. Vegan diets were lowest at 2.9 kg.
Within seafood, your choices matter. Small fish like anchovies and sardines, along with shellfish like mussels, oysters, and scallops, have a much smaller environmental impact than large, wild-caught species. Farmed shellfish in particular are among the most sustainable animal proteins available, since mussels and oysters filter water as they grow and require no feed inputs.
Building Meals in Practice
A well-rounded pescatarian week doesn’t need to revolve around fish at every meal. The core is plant-based: grain bowls with beans, vegetable stir-fries with tofu, pasta with tomato sauce, salads with eggs or cheese. Seafood slots in two to four times a week, depending on preference and budget.
For protein variety, the building blocks are straightforward:
- Seafood: salmon, shrimp, canned sardines, canned tuna (light, for lower mercury), cod, mussels
- Legumes: lentils, chickpeas, black beans, edamame
- Dairy and eggs: Greek yogurt, cottage cheese, eggs, cheese
- Nuts and seeds: almonds, walnuts, chia seeds, hemp seeds
- Whole grains: quinoa, oats, brown rice, farro
Canned fish is one of the most practical staples for this diet. Canned sardines and salmon are inexpensive, shelf-stable, high in omega-3s, and low in mercury. They work in salads, on toast, mixed into pasta, or straight from the can. If you’re transitioning from a meat-heavy diet and the main barrier is convenience, stocking your pantry with canned seafood and dried legumes solves most of the logistical challenge.