Yes, most seafood is keto. Fish, shrimp, crab and lobster contain almost no carbohydrate, so they fit any keto plan. Shellfish such as clams, mussels and oysters do contain some carbohydrate: per 100 g cooked, mussels have about 7.4 g and oysters about 9.9 g, according to USDA FoodData Central. Those still fit in normal portions, but count them on a strict plan. The things to watch are breadcrumbs, batter and sweet sauces.
Carbs and protein in seafood
Per 100 g, from USDA FoodData Central:
| Seafood (100 g) | Carbohydrate | Protein |
|---|---|---|
| Shrimp, cooked | 0.2 g | 24.0 g |
| Crab (Alaska king), cooked | 0 g | 19.4 g |
| Lobster, cooked | 0 g | 19.0 g |
| Squid, raw | 3.1 g | 15.6 g |
| Scallops, raw | 3.2 g | 12.1 g |
| Clams, cooked | 5.1 g | 25.6 g |
| Mussels, cooked | 7.4 g | 23.8 g |
| Oysters (Pacific), cooked | 9.9 g | 18.9 g |
| Salmon, farmed, raw | 0 g | 20.4 g |
Crustaceans (shrimp, crab, lobster) have essentially no carbohydrate. Mollusks (clams, mussels, oysters, scallops, squid) store some energy as glycogen, a form of carbohydrate, which is why they contain a little.
How much shellfish fits on keto?
Here’s what typical portions add, based on the values above:
| Portion | Carbohydrate |
|---|---|
| 150 g cooked shrimp | 0.3 g |
| 150 g cooked mussels (meat) | 11.1 g |
| 6 medium oysters (about 100 g meat, cooked) | 9.9 g |
| 100 g scallops | 3.2 g |
On a 20 g limit, a big bowl of mussels would use up more than half your allowance, so pair it with low-carb vegetables rather than bread or fries. Shrimp, crab and lobster can be eaten freely.
Keto-friendly seafood dishes
- Garlic butter shrimp with zucchini noodles.
- Grilled salmon or mackerel with a green salad and olive oil.
- Mussels in white wine and garlic with a side of greens instead of bread.
- Crab or shrimp salad with avocado and mayonnaise in lettuce cups.
- Seared scallops with sautéed spinach.
- Seafood stew with tomatoes, fish and shellfish, without potatoes.
Seafood to watch on keto
- Breaded or battered fish and shrimp, including fish fingers, fried calamari and tempura.
- Imitation crab (surimi), which often contains starch and sugar. Check the label.
- Sweet sauces: sweet chili, teriyaki, cocktail sauce and some marinades.
- Sushi rolls, because of the rice. Sashimi is the keto option.
Seafood safety
Cook seafood properly. The US Food and Drug Administration says most seafood should reach an internal temperature of 63°C (145°F). Shrimp, scallops, crab and lobster are done when the flesh turns firm, pearly and opaque. Clams, mussels and oysters are done when their shells open, and any that don’t open should be thrown away.
The FDA advises people at higher risk, including pregnant people, young children, older adults and anyone with a weakened immune system, to avoid raw or undercooked fish and shellfish. That includes raw oysters.
Mercury and how much to eat
Most shellfish and many fish are low in mercury. The FDA lists shrimp, salmon, sardines, scallops, clams, crab and oysters among its “best choices”. It advises limiting the highest-mercury fish: king mackerel, marlin, orange roughy, shark, swordfish, tilefish from the Gulf of Mexico and bigeye tuna.
The FDA recommends at least 8 ounces (about 225 g) of seafood a week for adults on a 2,000 calorie diet. If you’re pregnant or breastfeeding, the advice is 8 to 12 ounces a week from the lowest-mercury choices.
Why seafood is a good keto choice
Seafood gives you protein without carbohydrate, and oily fish adds omega-3 fats. Per 100 g, farmed Atlantic salmon has about 2 g of EPA and DHA combined, according to USDA values. Our guides to omega-3 foods and healthy fats on keto explain why that matters.
Allergy note
Shellfish is one of the major food allergens listed by the FDA. A shellfish allergy can be severe, so never “test” a food you’ve reacted to before, and check labels for shellfish in sauces, stocks and seasonings.
Common questions
Is canned tuna keto?
Yes. Plain canned tuna in water or oil has no carbohydrate. The FDA includes canned light tuna in its best choices for low mercury.
Can I eat sushi on keto?
Sashimi (raw fish without rice) is keto-friendly, as long as you’re not in a higher-risk group for raw seafood. Sushi rolls and nigiri contain rice, which is high in carbohydrate.
Before you start
Safety note: Keto isn’t suitable for everyone. If you have diabetes, kidney or liver disease, take regular medication, or are pregnant or breastfeeding, talk to your doctor before cutting carbs this far (why it matters).
A simple keto shrimp dinner
Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a large pan. Add 3 sliced garlic cloves and a pinch of chili flakes, then 400 g (14 oz) of raw peeled shrimp. Cook for 2 to 3 minutes, turning once, until the shrimp are pink and opaque all the way through. Squeeze over half a lemon, add chopped parsley and serve with zucchini noodles or a big green salad. It serves 2 and has only a few grams of net carbs per serving, mostly from the garlic and lemon.
Common questions
Is fish keto?
Yes. Plain fish, whether white fish such as cod or oily fish such as salmon and mackerel, has no carbohydrate. Watch out only for coatings and sauces.
How often can I eat shellfish on keto?
As often as you like within a varied diet, as long as you choose lower-mercury options and count the carbohydrate in mussels and oysters. The FDA’s advice for seafood each week applies on keto too.
Are frozen shrimp and fish just as good?
Yes. Plain frozen seafood has the same nutrition as fresh and is often cheaper. Thaw it in the fridge, not on the counter, and check that there’s no added glaze, batter or sauce.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
