Fish & Seafood

Tuna, especially yellowfin and skipjack, tops the list at around 24–28 g of protein per 100 g cooked. Other high-protein options include anchovies (around 28 g), shrimp (around 24 g), and salmon (around 22–25 g). Lean white fish like cod and haddock deliver roughly 20–23 g with very little fat.

Yes, nearly all fish and shellfish contain zero or trace carbohydrates, which fits standard keto macros. Fatty fish like salmon, mackerel, and sardines are especially useful because they provide both protein and omega-3 fats. Exceptions to watch are breaded or battered preparations and imitation crab (surimi), which contain added starch and sugar.

Cold-water fatty fish lead by a wide margin: mackerel, herring, and salmon provide roughly 2–4 g of combined EPA and DHA per 100 g, while sardines and anchovies deliver around 1.5–2 g. Shellfish contain smaller amounts, typically 0.2–0.5 g per 100 g, with oysters and mussels among the higher options.

Mercury content varies by species and size. Lower-mercury choices include shrimp, salmon, sardines, anchovies, cod, tilapia, scallops, and oysters. Higher-mercury species include swordfish, king mackerel, shark, marlin, and bigeye tuna, while albacore and yellowfin tuna fall in the moderate range. Smaller, shorter-lived fish generally accumulate less mercury than large predators.