Lake vs. Ocean Fish: What You Need to Know

lake ocean fish differences

Peaceful, freshwater lakes are very different places from the vast, rushing oceans of the world. That means that the creatures who live in them are different, too. You already know that most fish are divided into lake (freshwater) fish or ocean (saltwater) fish. But what are the key differences between the two, and what does it mean for you?

We’ve rounded up the most common differences and explained them for you below so you’ll be more informed next time you’re shopping for seafood.

Differences in Nutrients

Freshwater fish and saltwater fish are quite similar when it comes to their nutritional content; however, freshwater fish may have a slight advantage. Lake fish are generally higher in calcium and monounsaturated and polyunsaturated fatty acids than ocean fish. And for fish that live in both fresh and salt water, the freshwater variants tend to contain more vitamin A and folate.

However, contrary to popular belief, saltwater fish don’t actually have a much higher sodium content than freshwater fish. This is because even though they’re raised in saltwater, fish have an internal regulatory system that prevents sodium from the water from being absorbed by their flesh.

Differences in Taste

Fish Market Ocean Vs Lake Fish

Even though ocean fish don’t absorb the sodium from the water that surrounds them, saltwater fish tend to have a much brinier, “fishy” taste than their freshwater counterparts. However, most freshwater fish lack this briny flavor, making it a milder option for those who aren’t big on tasting the flavors of the ocean. Freshwater fish vary in their flavor profiles, but their light, subtle flavors are versatile enough for any fish dish, from fish tacos to crockpot stews.

Differences in Mercury Levels

Many people have questions about mercury levels in freshwater fish, especially when it’s being eaten by pregnant women, nursing mothers, or young children. Freshwater contains more mercury than saltwater, so it’s natural to assume that freshwater fish would contain more mercury, too.

But as it turns out, that’s not the case. In freshwater, mercury tends to latch onto decayed plant and animal matter, where sunlight can easily break it down. So even though there’s some mercury content in the water, it doesn’t stay in the fish.

Differences in Bone Structure


It may be hard to tell an ocean fish from a lake fish just by looking at its outside body, but if you take a look inside the fish you’ll probably notice a difference in their bones. Saltwater fish tend to have larger bones, making them easy to de-bone at the dinner table or on the butcher’s block. On the other hand, freshwater fish tend to have smaller bones, which means they require a bit more time and care to debone.

Whether your preference is for ocean fish or saltwater fish, you’re still getting a healthy serving of omega-3s and protein, amongst a lot of other nutrients. If reading about fish has made you hungry, check out our favorite fish recipes for some dinner inspiration!

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