Farm-Raised vs. Wild-Caught Fish

fish farming2large-school-of-fish

From nutrition to sustainability to cost to contaminants, there’s a lot to consider when weighing the pros and cons of farm-raised vs. wild-caught fish. 

Most people today are eating more fish as a healthy alternative.  Eating at least two servings of fish or shellfish per week appears to reduce the risk of heart disease, delay the onset of Alzheimer’s and dementia.  

Although meat, poultry, and fish are all good sources of protein, seafood boasts the healthiest fatty acid profile: it’s low in saturated fat and high in those omega-3 fats we hear so much about.

When you get to the fish counter, however, you’ve got some decisions to make. In particular: should you buy wild-caught or farm-raised fish? Many assume that wild-caught fish must be a lot better for you because it’s more “natural.”  But is this necessarily the case? And what about environmental issues, food safety, sustainability, and cost? With this many factors to consider, it’s impossible to make a blanket recommendation. Choosing between wild-caught and farm-raised fish depends on what kind of fish you’re buying, as well as where and how it is fished (or farmed). 

Is Wild-Caught Fish More Nutritious?


Today’s farmed Atlantic salmon provide significantly more omega-3 fats than wild-caught. 

The nutritional differences between wild and farmed fish are not as great as you might imagine. Farmed and wild-caught rainbow trout, for example, are almost identical in terms of calories, protein, and most nutrients. There are some minor differences: Wild-caught trout have more calcium and iron. Farmed-raised trout have more vitamin A and selenium. But for the most part, they are nutritionally equivalent. 

One of the main reasons we eat fish, of course, is that they are a uniquely potent source for long-chain omega-3 fatty acids. And here, farmed fish often have the advantage. Today’s farmed Atlantic salmon provide significantly more omega-3 fats than wild-caught Atlantic salmon, for example. 

The color of the flesh is not a reliable guide to omega-3 content, by the way. Atlantic salmon (whether fished or farmed) is a pale orange, while Sockeye is dark red. The paler Atlantic salmon provides more omega-3. 

Are Farm-Raised Fish Higher in Contaminants?

In 2004, a widely-cited study found the levels of PCBs, a potentially carcinogenic chemical, to be ten times higher in farmed fish than in wild-caught fish. That sounds pretty scary, but the amount of PCBs in the farmed fish was still less than 2% of the amount that would be considered dangerous. The differences may also have been exaggerated. Subsequent studies found PCB levels in farmed fish to be similar to those of wild fish. 

What about antibiotics or hormones? 

Are fish farmers dumping drugs and other chemicals into the ponds to maximize harvests? According to Linda O’Dierno, who is an Outreach Specialist for the National Aquaculture Association, U.S. regulations prohibit the use of hormones or antibiotics to promote growth in farmed fish. This is not necessarily the case in other countries. 

U.S. regulations prohibit the use of hormones or antiobiotics to promote growth in farmed fish although other countries have different legal standards.

The other contaminant that most people worry about with fish is mercury. The fish that present the biggest concern (swordfish, king mackerel. tilefish, shark, and tuna) are all wild-caught. The most common farm-raised fish (catfish, tilapia, and salmon) all have low or very low mercury levels.

The Health Risks of Mercury in Seafood

Mercury is a highly toxic heavy metal that can damage the central nervous system of children and unborn foetuses, slowing development of walking and talking and decreasing memory and attention span. Adults may experience headaches, fatigue, lack of concentration, and numbness in their hands and feet.

Once mercury enters the water, bacteria there chemically alter the mercury, creating a highly toxic substance called methylmercury. Small fish eat or absorb the methylmercury and are eaten in turn by bigger fish, which are then eaten by even bigger fish. As mercury moves up the food chain, it accumulates. As a result, larger predator fish, such as sharks and swordfish, tend to contain higher levels of mercury than salmon and other fish farther down the food chain.

Fish with the Highest Levels of Mercury

King Mackerel




Fish and Seafood with Mid-Range Mercury Levels

Tuna (all varieties except skipjack)

Orange Roughy



Spanish Mackerel

Chilean Seabass



Weakfish (sea trout)



Striped Bass or Rockfish

Fish and Seafood with Low Mercury Levels




Freshwater perch


Canned light tuna (skipjack)

Spiny lobster


Boston or Chub Mackerel





American shad



Fish and Seafood with Very Low Mercury Levels



Flounder, fluke, plaice, sand dabs











Are Farm-Raised Fish Genetically Modified?

cartoon fish

It is also widely believed that farm-raised fish are genetically modified–yet this is not the case. You may have read, for example, about striped bass that have a zig-zag in their stripes. These fish do exist but they are not genetically modified. They are simply a cross between striped bass and white bass–done the old-fashioned way.

However…several companies, including Monsanto have developed GMO fish, specifically Salmon and they are in the process of marketing the GMO fish worldwide.  

NOTE: Kroger and Safeway, the two largest conventional grocery store chains in the U.S., have made commitments to not sell genetically engineered salmon. These stores join other leading supermarket chains — now totalling over 9,000 stores nationwide — that have already rejected the GMO salmon under review by the FDA.



Australian Marine Conservation Society

Support Sustainable Seafood!

We’re at a point in time where there simply aren’t plenty more fish in the sea. With over three-quarters of our global fish stocks either over-exploited or fished right up to their limit, there are only a few fisheries that will be able to serve up the planet’s increasing demand for seafood.

Aquaculture, or farming seafood is often held up as the solution to the global fishing crisis, and indeed, the aquaculture sector is rapidly expanding globally – between 1980 and 2010, world aquaculture fish production expanded by almost 12 times1. 

However, with a continued requirement for wild caught fish to feed fish grown in captivity, there is still a cap on how much farmed produce can provide.

The good news is that we can lessen our impact on our oceans by choosing our seafood wisely. The fish you choose directly affects the health of our oceans. 

If you love our oceans but also love seafood, then you need Australia’s Sustainable Seafood Guide. It is the country’s first independent tool to choosing your seafood wisely and is now available online .


Put simply, ‘sustainable seafood’ is fish or shellfish that reaches our plates with minimal impact upon fish populations or the wider marine environment. It’s not just the numbers of fish left in the ocean that matters, it’s the way in which the fish are caught, the impact on the seafloor, other marine wildlife and how fishing affects the healthy and natural functioning of marine ecosystems.

Globally, we still have some way to go in achieving sustainable fisheries; poor management, lack of knowledge and the race to make a buck from fishing has led to overfishing and too high a burden on other ocean inhabitants. Bycatch, where species other than those being targeted for sale are caught up in fishing gear, kills hundreds of millions of animals every year, including unwanted fish, corals, turtles, dolphins and seabirds.

Fortunately, there is now growing demand for sustainable seafood – seafood caught or farmed responsibly, at fishing levels that allow fish stocks to maintain their populations and without jeopardising the ecosystem in which they live.

Sustainable seafood can be wild caught or farmed in aquaculture. For wild caught fish, sustainable seafood is generally sourced from fast growing, highly productive species that are caught by methods which don’t damage ocean habitats or catch large volumes of non-target species. Sustainably farmed seafood is usually grown in small, closed aquaculture systems that neither destroy coastal habitats or depend on wild caught fisheries for feed.

Very few fisheries are actually certified as sustainable throughout the world. The uncomfortable truth is that fishing is taking a huge toll on our oceans. Our global marine wildlife is under pressure from overfishing, destructive fishing gear and poor aquaculture practices. Not only are modern fisheries removing many of the fish from the sea, but non-target marine wildlife and ocean habitats are being destroyed in the process.

Thankfully, consumer demand for sustainable, environmentally friendly fish products is beginning to create momentum for a change in the way our fisheries and managed and caught.

Australia’s Sustainable Seafood Guide helps you take the first steps on the journey of discovering sustainable seafood.

Find out more about sustainable seafood at  

Australian Government – Fisheries Research & Development Corporation Atlantic Salmon Health in Australia – project 2007-246.pdf