Which fish is lowest in carbs? Your ultimate guide to zero-carb seafood

November 4, 2025 •

3 min read

According to USDA data, the majority of unprocessed fin fish contain zero carbohydrates, making them a perfect fit for a ketogenic or low-carb diet. This straightforward fact makes answering the question of which fish is lowest in carbs relatively simple, though some important nuances exist for shellfish and preparation methods.

Quick Summary

Many popular fin fish like salmon, cod, and tuna contain zero carbs, providing excellent protein and healthy fats for a ketogenic diet. Careful preparation is key, as breading adds carbohydrates. Some shellfish contain trace carbs, so monitoring intake is important for strict low-carb plans.

Key Points

Zero-Carb Fin Fish: Most raw, unprocessed fin fish like salmon, tuna, cod, and halibut contain zero carbohydrates.
Shellfish Differences: Be aware that while most shellfish are low-carb, some (like oysters) contain trace amounts that should be tracked for very strict diets.
Preparation is Crucial: Avoid breading and sugary marinades; instead, use simple cooking methods like baking, grilling, and steaming to keep carbs at zero.
Nutrient-Dense Choice: Low-carb fish like salmon and mackerel are packed with omega-3 fatty acids, high-quality protein, and essential vitamins.
Read Labels Carefully: Always check canned or frozen fish for hidden carbs from additives or preservatives to ensure your meal remains low-carb.
Versatile for Diets: The vast number of low-carb fish and seafood options provides endless variety for healthy, flavorful meals.

The Zero-Carb Rule for Fin Fish

For anyone focusing on a low-carbohydrate lifestyle, the good news is that most fin fish are naturally carbohydrate-free. This includes a wide array of options available at your local market or fish counter. The key is to consume them in their raw or unadulterated state. Any preparation that involves flour, breadcrumbs, sugar, or high-carb glazes will, of course, add carbohydrates to the final dish. When prepared simply through baking, grilling, or steaming, the following fish are confirmed to have zero carbohydrates:

Cod: A lean, flaky white fish with a mild flavor, excellent for baking or broiling.
Salmon: A fatty fish rich in omega-3s, available wild-caught or farmed.
Tuna: Whether fresh or canned in water, tuna is a versatile and zero-carb protein source.
Trout: A delicious and slightly fattier freshwater fish.
Haddock: Another lean white fish with a delicate flavor, similar to cod.
Halibut: A firmer, meatier white fish with a very low-fat content.
Mackerel: An oily, flavorful fish packed with nutrients and omega-3s.
Sardines: These small, oily fish are incredibly nutrient-dense and low in carbs.
Mahi-Mahi: A firm white fish with a sweet, mild taste, great for grilling.

The Exception: Carbohydrates in Shellfish

While most fin fish are uniformly carb-free, the category of seafood known as shellfish requires a closer look. Most shellfish are very low in carbohydrates, but some varieties contain trace amounts. For those on a very strict keto or zero-carb diet, it is important to be aware of these small differences.

Shrimp: Typically contains zero carbs, though some processed or frozen products may have additives.
Crab: Contains virtually no carbohydrates in its natural state.
Lobster: Also a zero-carb option when cooked simply.
Mussels: Have a very low carbohydrate count, with some sources listing trace amounts.
Oysters: These have a slightly higher carb count than other shellfish, so tracking is necessary for strict low-carb diets.

Comparison of Popular Low-Carb Fish (per 100g raw)


Fish Type	Carbs (g)	Fat (g)	Protein (g)	Notable Benefit
Cod (Atlantic)	0	0.7	18	Lean and mild
Tuna (Yellowfin)	0	<1	24	High protein
Halibut	0	3	20	Meaty and firm
Salmon (Wild)	0	12	22	Rich in Omega-3s
Mackerel	0	20	27	High in Vitamin D and Omega-3s

Optimizing Your Cooking for Carb Control

The preparation method is often the main source of unwanted carbohydrates when eating fish. To keep your meal as low-carb as possible, follow these tips:

Stick to Simple Cooking: Baking, broiling, grilling, and steaming are the best methods. Use olive oil, herbs, and lemon juice for flavor instead of sugary sauces.
Avoid Breadings: Flour and breadcrumbs are high in carbohydrates and should be avoided. A low-carb alternative can be a crust of crushed pork rinds or almond flour, but always check the carb count.
Read Labels Carefully: When buying canned or frozen fish, especially flavored varieties, check the nutrition label for added sugars, starches, or other hidden carbs. Canned tuna packed in water is typically a safe bet for zero carbs.

Health Benefits Beyond Low Carbs

Including low-carb fish in your diet offers significant health advantages beyond carbohydrate restriction. These benefits come from the high-quality protein and healthy fats that fish provide.

Rich in Omega-3 Fatty Acids: Fatty fish like salmon, mackerel, and sardines are excellent sources of EPA and DHA, which are beneficial for heart health and reducing inflammation.
High-Quality Protein: Fish is a complete protein, meaning it contains all the essential amino acids your body needs. Protein is crucial for muscle maintenance, satiety, and overall body function.
Essential Vitamins and Minerals: Fish provides a host of essential nutrients, including Vitamin D, Vitamin B12, iodine, and selenium, which many people are deficient in. To learn more about the extensive health benefits of these fatty acids, visit the National Institutes of Health (NIH) website.

Conclusion: The Final Word on Low-Carb Fish

When asking, "Which fish is lowest in carbs?" the answer is a simple one: nearly all fin fish contain zero carbohydrates when prepared without added starches or sugars. This makes fish an ideal and versatile protein source for anyone following a ketogenic or low-carb diet. While most shellfish are also excellent choices, a few types like oysters contain trace carbs, which should be considered for strict dietary tracking. By choosing unprocessed fish and simple cooking methods, you can enjoy a wide variety of delicious seafood while easily maintaining your carb goals and reaping numerous health benefits.

Frequently Asked Questions

Yes, canned tuna is an excellent low-carb option, as long as you choose varieties packed in water and avoid brands with added flavorings containing sugar. For example, a 5 oz can of chunk light tuna in water has zero carbohydrates.

The best way is to check the nutritional label of any packaged or frozen fish product. Look for the 'Total Carbohydrates' line. If you are ordering at a restaurant, ask the server if the fish is prepared with breading, flour, or sugary glazes.

Most shellfish, including shrimp, crab, and lobster, are carb-free. However, some, like oysters and mussels, contain very small, trace amounts of carbohydrates. For most people, this is insignificant, but those on a strict keto diet may need to monitor their intake.

Both wild-caught and farmed fish are generally zero-carb. The main difference lies in their fat content and omega-3 profiles. Wild-caught fish are often leaner, while farmed fish can be fattier. The carb count remains zero for both in their natural state.

No, traditional fish and chips is not a low-carb meal. The fish is typically coated in a flour-based batter, which is high in carbohydrates. To make it low-carb, you would need to cook the fish without any breading.

Cod and tilapia are excellent choices for beginners. They both have a mild, non-fishy flavor and are very lean, making them versatile for many recipes without overpowering the dish.

Perfect low-carb sides for fish include roasted broccoli, sautéed spinach, asparagus, or a fresh avocado salad. These pairings complement the flavor of the fish while keeping your meal free of unwanted carbohydrates.