Nearly all fresh fish is naturally low in sodium. A typical 3-ounce cooked serving of finfish contains less than 100 milligrams, making it one of the lowest-sodium protein sources available. The real sodium spikes come from how fish is processed, packaged, and prepared, not from the fish itself.
Lowest-Sodium Fresh Fish
Fresh, unprocessed finfish is where you’ll find the best sodium numbers. Rainbow trout comes in at just 43 milligrams per cooked fillet. Raw tilapia is similarly low at about 60 milligrams per fillet. Catfish contains roughly 47 milligrams per 3-ounce raw serving, and Alaskan pollock sits around 60 milligrams for the same portion.
Fresh salmon is another strong option at approximately 75 milligrams per 3.5-ounce serving. Fresh tuna is remarkably low, with only about 13 milligrams per ounce. Cod and flounder tend to run slightly higher in their raw state but still fall well under 100 milligrams per serving. For context, the FDA defines “low sodium” as 140 milligrams or less per serving, so fresh finfish easily clears that bar.
Shellfish Has Significantly More Sodium
If you’re watching your sodium intake, the distinction between finfish and shellfish matters. Most shellfish contains between 100 and 500 milligrams of sodium per 3-ounce cooked serving. Raw shrimp has about 481 milligrams per serving. Clams come in around 511 milligrams, and blue crab sits near 249 milligrams. These numbers can be three to ten times higher than a comparable portion of fresh finfish.
Oysters are the exception among shellfish, with roughly 151 milligrams per raw serving. That’s still higher than most fresh fish but far lower than shrimp or clams. If you enjoy shellfish and want to keep sodium in check, oysters are your best bet.
Processing Adds Hundreds of Milligrams
The way fish is handled after it leaves the water makes a dramatic difference. Smoked salmon contains 600 to 1,200 milligrams of sodium per 3.5-ounce serving, compared to just 75 milligrams for the same amount of fresh salmon. That’s up to 16 times more sodium from smoking and curing alone.
Canned fish follows a similar pattern. Canned tuna packed in water contains about 70 milligrams of sodium per ounce, while fresh tuna has only 13 milligrams per ounce. Canned tuna packed in oil is even higher at 118 milligrams per ounce. Canned salmon with the liquid drained still delivers around 324 milligrams per 3-ounce serving.
Frozen fish fillets can also be a hidden source of sodium. Many commercially frozen fillets are treated with a brine solution before freezing. These solutions typically contain water, salt, and phosphate compounds that help the fish retain moisture and reduce thaw drip. The result is a fillet that looks and feels like fresh fish but carries a significantly higher sodium load. Always check the nutrition label on frozen fish, and look for products labeled “no added sodium” or those with short ingredient lists that don’t include salt or phosphate additives.
How to Compare at the Store
The general rule is simple: the less a fish has been processed, the less sodium it contains. Here’s how different forms of fish stack up:
- Fresh fillets (best choice): Under 100 mg per serving for virtually all finfish species
- Plain frozen fillets without additives: Similar to fresh, but check labels for brine or phosphate treatments
- Canned in water: Moderate sodium, typically 200 to 400 mg per serving
- Canned in oil or brine: Higher sodium, often 300 to 500 mg per serving
- Smoked, cured, or dried: Highest sodium, 600 mg and above per serving
The recommended daily sodium limit for adults is less than 2,300 milligrams. A single serving of smoked salmon can account for over half of that limit, while a serving of fresh trout or tilapia uses up less than 3 percent.
Flavoring Fish Without Adding Sodium
The challenge with low-sodium fish is that people often reach for salt or salty sauces to add flavor. A few easy swaps can keep your meal flavorful without undoing the sodium advantage of fresh fish.
Lemon juice is one of the most effective alternatives. Acid works similarly to salt by bringing out the natural flavors in food, and lemon zest adds an even more concentrated citrus punch. Lime and orange juice have the same effect. Dill pairs particularly well with fish and is one of the most traditional salt-free seasonings for salmon and white fish. Fresh or dried garlic boosts flavor without adding any sodium, and black pepper on its own can carry a dish that would normally rely on salt.
For bolder flavors, try ginger in marinades, smoked paprika for a deeper warmth, or red pepper flakes for heat. Rosemary and tarragon both work well with fish, especially in butter or cream-based preparations. Onion powder is more potent than fresh onion and adds savory depth to stir-fries and baked fillets. These seasonings let you build complex flavors while keeping your total sodium count low.
Best Overall Picks
If sodium is your primary concern, fresh rainbow trout, tilapia, catfish, pollock, tuna, and salmon are all excellent choices, each containing well under 100 milligrams per serving. Buy them fresh or frozen without additives, season with citrus and herbs, and you have one of the most heart-friendly protein options available. The fish you choose matters far less than how it was processed. A fresh fillet of nearly any species will be low in sodium. A smoked, cured, or heavily brined version of that same fish will not.