A 3-ounce (84g) serving of cooked haddock contains about 21 grams of protein, making it one of the most protein-dense foods you can eat relative to its calorie count. That single serving delivers roughly 100 calories, meaning protein accounts for the vast majority of the energy in this fish.
Protein Per Serving and Per 100 Grams
The FDA lists cooked haddock at 21 grams of protein per 3-ounce serving prepared with no added fat or ingredients. Scaled to 100 grams, that works out to roughly 25 grams of protein. For context, a typical haddock fillet weighs between 5 and 7 ounces, so a full fillet gives you somewhere around 35 to 49 grams of protein in a single piece of fish.
That protein-to-calorie ratio is hard to beat. With only about 100 calories per 3-ounce serving and virtually no fat, haddock delivers more protein per calorie than chicken breast, eggs, or most dairy sources. If you’re tracking macros or trying to hit a protein target without excess calories, haddock is an efficient choice.
Keep in mind that cooking method changes the final numbers. Breading and frying adds carbohydrates and fat that dilute the protein percentage. Baking, broiling, poaching, or steaming keeps the nutritional profile close to those baseline figures.
How Haddock Compares to Other White Fish
Haddock sits in a tight cluster with cod, pollock, and tilapia when it comes to protein. All of these white fish deliver roughly 20 to 22 grams of protein per 3-ounce cooked serving, with calorie counts hovering around 100 and cholesterol under 70 milligrams. The differences between them are small enough that choosing one over another is mostly a matter of taste, texture, and price.
Where haddock does stand out slightly is in its micronutrient profile. Compared to tilapia, haddock tends to carry more B12 and selenium. Compared to cod, the two are nearly interchangeable nutritionally, though haddock has a slightly sweeter, more delicate flavor that some people prefer.
Protein Quality in Haddock
Not all protein is equal. What matters beyond the gram count is whether a food contains all nine essential amino acids your body can’t produce on its own. Fish, including haddock, is a complete protein source. Your body can use it efficiently for muscle repair, immune function, and enzyme production without needing to combine it with other foods.
This makes haddock particularly useful for older adults trying to preserve muscle mass, people recovering from surgery or illness, and anyone following a high-protein diet. The protein in fish is also highly digestible compared to plant-based sources, so your body absorbs a greater share of what you eat.
Other Nutrients You Get With the Protein
A 3-ounce serving of haddock delivers more than just protein. It covers 89% of your daily value for vitamin B12, a nutrient essential for nerve function and red blood cell production that many people, especially those over 50, run low on. The same serving provides 58% of your daily selenium, which supports thyroid function and acts as an antioxidant, along with 40% of your daily phosphorus, important for bone health.
You get all of this for about 100 calories and very little saturated fat. Haddock is also naturally low in sodium unless it’s been smoked or cured (as in the case of finnan haddie, a traditional smoked preparation that significantly raises sodium content).
Mercury Levels in Haddock
Mercury is a reasonable concern with any seafood, but haddock falls firmly in the low-mercury category. FDA testing of 50 samples of Atlantic haddock found an average mercury concentration of 0.055 parts per million, with some samples showing no detectable mercury at all. For comparison, high-mercury fish like swordfish and king mackerel typically test above 0.7 ppm.
At those low levels, most people can safely eat haddock two to three times per week. Pregnant women and young children, who are most sensitive to mercury, can still include haddock as one of their regular fish choices without concern, as it falls well within the FDA’s “best choices” range for low-mercury seafood.
Simple Ways to Maximize the Protein
If you’re eating haddock specifically for the protein, preparation matters. Baking a fillet at 400°F for about 12 to 15 minutes with a squeeze of lemon preserves the full protein content without adding significant calories. Poaching in broth or water works just as well. Pan-searing with a light coat of oil adds minimal fat while giving you a crisp exterior.
Battering and deep-frying, the classic fish-and-chips approach, roughly doubles or triples the calorie count while adding carbohydrates and fat. The protein is still there, but the ratio shifts dramatically. If you enjoy breaded haddock, a light breadcrumb coating baked in the oven is a reasonable middle ground that keeps the protein-to-calorie balance favorable.