Fresh fish is one of the lowest-sodium proteins you can eat. A 3-ounce serving of most finfish contains just 30 to 110 mg of sodium, which is a small fraction of the 2,300 mg daily limit recommended by the American Heart Association. The catch is that processing, curing, and cooking methods can multiply that number dramatically.
Sodium in Common Finfish
According to FDA nutrition data, here’s what you get in a 3-ounce cooked serving of popular fish (prepared without added salt or seasoning):
- Tilapia: 30 mg
- Rockfish: 40 mg
- Orange roughy: 45 mg
- Catfish: 50 mg
- Tuna: 50 mg
- Salmon (Atlantic, coho, sockeye): 55 mg
- Rainbow trout: 55 mg
- Halibut: 70 mg
- Haddock: 85 mg
- Cod: 95 mg
- Flounder/sole: 100 mg
- Pollock: 110 mg
For context, the same 3-ounce portion of deli turkey can contain 700 to 1,000 mg of sodium. Even the highest-sodium finfish on this list delivers less than 5% of your daily recommended limit. If you’re watching sodium for blood pressure or kidney health, fresh fish is consistently a safe choice.
Shellfish Is a Different Story
Shellfish naturally contains significantly more sodium than finfish. The same 3-ounce cooked serving tells a very different story:
- Lobster: 470 mg
- Blue crab: 330 mg
- Scallops: 310 mg
- Oysters: 300 mg
- Shrimp: 240 mg
- Clams: 230 mg
Lobster stands out here. A single 3-ounce serving delivers about 20% of the daily sodium limit before you add drawn butter or any seasoning. Shrimp and clams are more moderate but still carry roughly four to five times the sodium of a comparable piece of salmon or tilapia. None of these numbers are alarming on their own, but they add up quickly in a shellfish-heavy meal, especially a seafood boil or platter where portions are generous.
Where Fish Gets Salty: Processing and Canning
The real sodium spike happens after fish leaves the water. Canning, smoking, and curing transform a low-sodium food into a high-sodium one.
A single ounce of smoked salmon (lox) contains 567 mg of sodium. That means a typical 3-ounce bagel portion delivers around 1,700 mg, nearly 75% of your daily limit in one sitting. The brining and smoking process is responsible for this jump. Fresh salmon of the same weight would contain about 55 mg.
Canned tuna also picks up sodium during processing. One ounce of raw tuna has about 13 mg of sodium. The same amount of canned tuna in water has 70 mg, and canned tuna in oil reaches 118 mg. Those numbers are still relatively modest per ounce, but a full can adds up. Look for cans labeled “low sodium” or “no salt added” if you eat canned tuna regularly.
Frozen Fish and Hidden Additives
Frozen fish fillets sometimes contain more sodium than you’d expect from reading the species name alone. Many processors soak fillets in a sodium-based solution (sodium tripolyphosphate) before freezing. This chemical helps the fish retain moisture, prevents the texture loss that comes with freezing, and reduces the liquid that drips out when you thaw it. The result is a plumper-looking fillet that also happens to carry more sodium than a fresh piece of the same fish.
The ingredient list on the package will tell you if this additive was used. If you see “sodium tripolyphosphate” or “STPP,” expect the sodium count to be higher than the values listed above for plain cooked fish. Choosing untreated frozen fish or buying fresh is the simplest way to avoid this.
Sauces and Marinades Add the Most
The biggest sodium contributor in most fish dishes isn’t the fish itself. It’s what goes on top. A single tablespoon of soy sauce contains 920 to 1,100 mg of sodium. Fish sauce is even worse, at 1,190 to 1,500 mg per tablespoon. Sweet and sour sauce ranges from 800 to 1,000 mg per tablespoon.
That means a teriyaki-glazed salmon fillet or a fish stir-fry can easily cross 1,500 mg of sodium for the whole dish, even though the fish underneath contributed less than 60 mg. If you’re trying to keep your meal low-sodium, using reduced-sodium soy sauce, citrus-based marinades, or herb rubs makes far more difference than which species of fish you choose.
Best Low-Sodium Fish Choices
If you’re specifically looking for the lowest-sodium options, stick with finfish and choose species at the bottom of the range. Per the National Kidney Foundation’s data (per 3.5-ounce serving), these are the best picks:
- Bluefin tuna: 50 mg
- Tilapia: 56 mg
- Rainbow trout: 61 mg
- Black cod (sablefish): 72 mg
- Perch: 79 mg
All of these fall well under 100 mg per serving, making them excellent protein choices for people on sodium-restricted diets. Season with lemon, garlic, fresh herbs, or black pepper to keep the sodium count low while still getting a flavorful meal. The AHA’s ideal target of 1,500 mg per day for most adults leaves plenty of room for a serving of any fresh fish, as long as the rest of the plate cooperates.