White fish like cod, haddock, pollock, tilapia, and sole are the leanest fish you can eat, with most containing less than 1 gram of fat per serving. Shellfish like shrimp, scallops, and crab are similarly lean, with 15 percent or fewer of their calories coming from fat. If you’re looking for a high-protein food that fits into a low-fat diet, these are your best options.
Why Some Fish Are So Much Leaner Than Others
The difference comes down to where a fish stores its fat. White fish, like the entire cod family, store almost all of their fat in the liver rather than in the muscle tissue you actually eat. That’s why cod liver oil exists as a supplement but a cod fillet is practically fat-free. The fat content of white fish muscle stays below 1 percent year-round, and even seasonal changes in the fish’s body fat show up in the liver, not the flesh on your plate.
Fatty fish like salmon, mackerel, and herring work differently. They carry fat throughout their muscle tissue, particularly in the darker strips of muscle running along their bodies. These dark muscle bands are much larger in fatty fish and contain higher concentrations of both fat and certain vitamins. A 3-ounce serving of salmon can have 10 to 12 grams of fat, while the same amount of cod has less than 1 gram. Both are healthy choices, but they serve very different roles if you’re watching your fat intake.
The Leanest Fish Options
These white fish all fall into the ultra-lean category, generally under 2 grams of total fat per 3-ounce cooked serving:
- Cod: mild flavor, tender and flaky texture, widely available fresh and frozen
- Haddock: slightly sweeter than cod, similar texture, popular for baking and broiling
- Pollock: mild and affordable, commonly used in fish sticks and imitation crab
- Tilapia: very mild, firm enough to hold up on the grill, one of the most budget-friendly options
- Sole and flounder: delicate, thin fillets with a mild, slightly sweet taste
- Halibut: mild and sweet with a firm, meaty texture that works well as a steak-style cut
Among these, cod and pollock are the easiest to find at a reasonable price. Halibut tends to be significantly more expensive but offers a denser, more satisfying bite that some people prefer. Sole and flounder cook quickly because the fillets are thin, making them good weeknight options.
Shellfish Are Lean Too
Shellfish often get overlooked in conversations about low-fat eating, partly because of outdated concerns about cholesterol. But shrimp, clams, scallops, lobster, crab, and abalone are all genuinely low-fat, high-protein foods. Research from Washington Sea Grant confirms that 15 percent or fewer of the calories in these shellfish come from fat, and their saturated fat content is minimal.
Shrimp is the standout for accessibility. A 3-ounce serving has less than 1.5 grams of fat and roughly 20 grams of protein. Scallops are similarly lean and have a naturally sweet flavor that caramelizes well when seared. Crab and lobster fall in the same range, though they cost more. Any of these can anchor a low-fat meal without sacrificing flavor or satisfaction.
Mercury Levels in Lean Fish
Most of the leanest fish happen to be low in mercury as well, but not all of them. The FDA places cod, haddock, pollock, tilapia, sole, flounder, and most shellfish in its “Best Choice” category, meaning they have the lowest mercury levels and are safe to eat two to three times per week.
The notable exception is orange roughy. Despite being a lean white fish, it lands on the FDA’s “Choices to Avoid” list for having among the highest mercury levels of any fish. Orange roughy are deep-sea fish that live for decades, which gives mercury more time to accumulate in their bodies. If you’re eating fish regularly, skip orange roughy and stick with the other white fish on this list.
Low-Fat Fish vs. Fatty Fish
Choosing lean fish makes sense if you’re managing your overall fat or calorie intake. A serving of cod gives you around 70 to 90 calories and 15 to 20 grams of protein with almost no fat. That’s a better protein-to-calorie ratio than chicken breast in some preparations.
That said, the fat in oily fish like salmon and mackerel is rich in omega-3 fatty acids, which support heart and brain health. If your goal is specifically heart health rather than reducing total fat grams, fatty fish may actually serve you better. Many dietitians recommend eating both types: lean white fish for everyday low-calorie meals, and fatty fish once or twice a week for the omega-3 benefits. The American Heart Association recommends at least two servings of fish per week, and a mix of lean and fatty fish is one practical way to hit that target.
Cooking Tips to Keep It Lean
The fish itself may be almost fat-free, but preparation matters. Breading and deep-frying a cod fillet can add 10 or more grams of fat per serving, which defeats the purpose. The best cooking methods for keeping lean fish lean are baking, broiling, steaming, poaching, and grilling. A squeeze of lemon, fresh herbs, and a light brush of olive oil is enough to bring out the mild, clean flavor these fish are known for.
One thing to watch with white fish is that their low fat content means they dry out faster than salmon or mackerel. Cooking to an internal temperature of 145°F and pulling the fish off heat promptly keeps the texture moist and flaky rather than tough. Poaching in broth or baking in parchment paper (known as “en papillote”) are particularly forgiving methods if you tend to overcook fish. Thin fillets like sole and flounder need only 3 to 5 minutes of cooking, so set a timer.