Should you be eating wild caught fish or is it still acceptable to purchase farmed? It’s a big question we face, particularly when we know we should likely be eating fish more frequently in our lives. Most nutrition recommendations suggest that we should have at least two fish or shellfish servings every week to prevent the onset of dementia and Alzheimer’s, reduce heart disease risk, and simply maintain overall health.

That said, when we get to the fish options at our grocery store, we quickly discover that there are wild caught fish and farmed fish from which to choose. Is there a difference? If so, what is the difference? Does it have to do with the nutrients you obtain? Is the contaminant level different and does it impact the environment differently? Fortunately, there are answers.

Is Wild Caught Fish or Farmed Fish More Nutritious?

Farmed fish contains different nutrient balances than wild caught fish. For example, farmed Atlantic salmon offers substantially higher omega-3 fatty acid levels than those caught from the wild. However, other than that specific example, the size of the nutritional differences between the two kinds of fish aren’t as large as you might think.

For example, when it comes to another common type of fish, rainbow trout, the calories, protein and majority of nutrients are nearly identical regardless of whether it’s farmed or wild caught fish. Farm raised has slightly more selenium and vitamin A and wild-caught has slightly more iron and calcium, but not enough to make much of a difference to your daily nutrition.

Which Fish is Higher in Contaminants and Environmental Impact?

When it comes to contaminants, there is a bit of controversy over the difference between farmed and wild caught fish. A well reputed study from 2004 showed that there are ten times the level of PCBs (a potentially carcinogenic – that is, cancer-causing – chemical) in farmed fish than in those caught in the wild.

That said, it’s important to note that the PCBs level in farmed fish was still only 2 percent of the amount at which it would be deemed dangerous to eat. Therefore, while one has ten times more than the other, the amount is still considered to be very safe to eat a few times per week. At the same time, a number of studies that have been conducted since 2004 have shown comparable PCB levels in both types of fish.

Mercury is the other top worry people have about contaminants in fish. Wild caught fish with the highest levels are tuna, shark, tilefish, king mackerel and swordfish. Farm raised with the highest levels are salmon, tilapia and catfish.

According to most studies, the environmental impact of wild caught fish and farm raised fish comes from different places, but when all is said and done, they’re considered about equal.