A 100-gram serving of raw haddock contains 18.91 grams of protein and just 87 calories, making it one of the leanest protein sources available. Once cooked, that number climbs because moisture evaporates and the protein concentrates into a smaller portion. A standard steamed fillet (140 grams) delivers about 28.8 grams of protein with less than 1 gram of fat.
Protein by Serving Size
Most people don’t weigh their fish in neat 100-gram portions, so here’s what common serving sizes look like. A 6-ounce cooked fillet, which is a typical dinner portion, provides roughly 32 grams of protein. A smaller 3-ounce portion, closer to what you’d get as a side or in a fish taco, delivers about 16 grams. That 6-ounce fillet covers nearly half your daily protein needs based on a 2,000-calorie diet.
For context, a single steamed haddock fillet has only 122 calories. Grilled bumps that to around 151 calories, and baked comes in at about 176 calories, largely depending on whether you add oil or butter. Even at the higher end, haddock gives you an exceptional protein-to-calorie ratio that’s hard to beat outside of egg whites or chicken breast.
How Haddock Compares to Other Fish
Haddock sits in the same protein range as cod, its closest relative on the plate. The two fish are so nutritionally similar that they’re often interchangeable in recipes, though haddock has a slightly sweeter flavor and finer texture. Sometimes sold under the name “scrod,” haddock is essentially a cod alternative with the same lean protein profile.
Where haddock really stands apart is against fattier fish. A steamed salmon fillet of comparable size runs about 332 calories, nearly three times what you’d get from haddock. Salmon does offer more omega-3 fatty acids, but if your goal is maximizing protein while keeping calories and fat minimal, haddock is the stronger choice. Other white fish like pollock and tilapia occupy a similar nutritional space, but haddock edges most of them out slightly on protein per serving.
How Cooking Affects Protein Content
The protein in haddock holds up well regardless of how you cook it. Research comparing baked and deep-fried fish found no significant difference in protein content when measured immediately after cooking. Both methods landed around 33% protein by weight on day zero.
The real difference is what frying adds. During deep-frying, water evaporates from the fish and gets partially replaced by oil soaking in. That nearly doubles the fat content compared to baking (about 11% fat for fried versus 6% for baked) without meaningfully increasing protein. Over time, baked fish actually retains a slight protein advantage because it holds onto more moisture without absorbing extra fat. So if you’re eating haddock specifically for the protein, baking, steaming, or grilling all preserve what you’re after. Frying doesn’t destroy the protein, but it dilutes the ratio by packing in calories from oil.
What Makes Haddock Protein High Quality
Not all protein is created equal. What matters beyond the gram count is whether a protein source contains all nine essential amino acids your body can’t produce on its own. Fish protein, including haddock, is a complete protein. White fish in general is rich in leucine and lysine, two amino acids that play key roles in muscle building and tissue repair. It also provides strong amounts of valine, isoleucine, and the sulfur-containing amino acid methionine.
Fish protein is also highly digestible. Your body absorbs and uses a greater percentage of protein from fish compared to many plant sources, where fiber and other compounds can slow absorption. This makes haddock particularly useful for older adults concerned about muscle maintenance, or anyone recovering from surgery or illness where efficient protein uptake matters.
Mercury and Safety
One reason people hesitate around seafood is mercury, but haddock is among the cleanest options. FDA monitoring data shows Atlantic haddock averages just 0.055 parts per million of mercury, with a maximum recorded level of 0.197 ppm across 50 samples. For comparison, the FDA’s action level for mercury in fish is 1.0 ppm. Haddock falls well below that threshold, putting it in the “best choices” category for frequency of consumption. You can safely eat haddock two to three times per week without concern, including during pregnancy.
Getting the Most Protein From Haddock
If you’re building meals around haddock for its protein content, a few practical tips help. Buy fillets rather than breaded or battered products, which add carbohydrates and fat while reducing the percentage of actual fish per serving. Frozen fillets retain essentially the same protein content as fresh, so don’t overpay at the fish counter if budget is a concern. A 6-ounce fillet baked with a squeeze of lemon and light seasoning gives you 32 grams of protein for under 180 calories, making it one of the most efficient protein sources in any grocery store.