15 Things You Need To Know About Farmed Fish

Fish farming, otherwise known as aquaculture, is one agricultural sector that has seen unprecedented growth globally and domestically. According to data collected by the Food and Agriculture Organization of the U.N. (FAO), global aquaculture production has increased by 527% between 1990 and 2018, with roughly half of the seafood imported to the United States being farmed (via the National Oceanic and Atmospheric Administration). Countries like China have seen the most prolific uptick in production, and as of 2013, more fish is farmed than is captured in the wild (per Our World In Data).

Aquaculture is not immune to consumer questions surrounding its practices and ethical complications — especially because of its sheer prevalence at grocery stores and fishmongers. But what exactly does it mean for a fish to be farm-raised, and why does your choice to purchase this growing method over wild-caught seafood matter? We're here to investigate some of the mysteries surrounding aquacultured fish and some of the benefits and drawbacks of choosing farm-raised during your next trip to the seafood counter.

While finfish (like salmon, tilapia, and catfish) encompass most aquaculture in the United States, farmed crustaceans and shellfish are also significant contributors to the domestic aquaculture economy. For example, freshwater crawfish are grown in the southern United States and often share rice paddies or wetlands with other agricultural operations. Manilla clams and mussels on grown in off-shore operations on the West Coast and hard-shelled clams are farmed on the East Coast.

Shrimp encompass ⅓ of aquacultural imports to the United States, with the top exporting countries being Thailand, Ecuador, Mexico, China, and Indonesia (via the United States Department of Agriculture). Shrimp aquaculture has trended upwards in recent years; the National Fisheries Institute's Global Seafood Market Conference's panel expected shrimp yield to be over five million megatons annually as of 2022 (via Seafood Source).

Edible fish is a large subsection of the aquaculture industry, but there are other uses for farm-raised fish. For example, saltwater ornamental species, like clownfish, are added to fish tanks, while some trout species are grown in hatcheries to restock rivers for recreational fishermen. Research species, like zebrafish, are a small sector of aquaculture as well.

There are many reasons why aquacultured fish are touted as a "sustainable" protein source. First, fish have a comparatively low feed conversion ratio, the amount of feed needed to produce a pound of body mass. Aquacultured fish's average feed conversion ratio is around 1.1-to-1, while the average for chicken, beef, and pork is anywhere from 2.1-to-10 (via Global Seafood). In recent years, there has also been a movement to use trimmings from processing plants and plant proteins to help support the demand for farm-raised fish. Fish also do not require the same amount of space as terrestrial livestock, meaning that fish can be grown in indoor recirculating systems or on marginal land where other agricultural activities cannot occur.

Many innovations can be made to help offset some of the environmental impacts of growing finfish, most notably waste. For example, farmers can grow species like seaweed to help soak up the extra nutrients in the water in a polyculture system.

Farmed fish isn't much healthier than wild-caught seafood. Besides the marginal differences in omega-3s, consumers can rest assured knowing they purchase nutritious fish, whether farm-raised or wild-caught. The protein and micronutrient levels of the two are very similar, with only a slight difference in the prevalence of fats. A 3-ounce filet of wild salmon has about half the fat and fewer calories than farmed salmon. Wild-caught fish also tend to be leaner in texture and lower in fat because they swim longer distances and can go without food during migrations or spawns.

One of the myths associated with fish is that the color directly reflects the fish's nutritional content. The color of the fish's flesh is controlled by two factors; myoglobin and diet. Myoglobin is responsible for storing oxygen in a fish's muscles. Red-fleshed fish, like tuna, snapper, and mahi mahi, have darker meat, while fish like tilapia and flounder are white because the latter move less. Fish that eat darker-colored food, like krill and shrimp, will have redder flesh. Since farm-raised fish do not have these crustaceans in their diet, the color of their meat is typically paler.

If you've ever eaten hydroponic lettuce, you've already tasted what else aquaculture can produce. Hydroponics, produce grown without traditional growth media like soil, is a valuable method of growing food to reduce the need for terrestrial space. Aquaponics is similar to hydroponics but is powered by the nutrients derived from fish waste. An entire aquaponics system can produce vegetables, like lettuce, radishes, and berries, and protein from fish. Aquaponics can be grown in numerous ways, including vertical farming, which uses gravity to move nutrient-rich water from one place to another.

Aquaponics is less common than hydroponically-grown produce because of the project's high capital investment and the knowledge needed to set up and manage an aquaponics system. Several communities around the United States have expressed interest in developing these aquaponic systems to utilize reclaimed land and create jobs (and food) for their residents — which is expected to help push aquaponics to flourish in coming years.

If you frequently purchase organic food at your grocery store, you may wonder why you can never find organic seafood. Wild-caught food cannot be considered organic because there is no control over what the fish eat and what kind of toxins they're exposed to. But since farmed seafood has a bit more human intervention, can't it be certified under the USDA's organic program?

There is currently no legislation or process for organic certification under the USDA's Organic Foods Production Act. In turn, this means that the USDA cannot seek legal penalties against any producer who markets their farm-raised (or wild-caught) fish as "organic." Yet, some companies still market their fish as "organic" because of the regulatory loophole. Several grocers like Whole Foods Market and governments like the state of California refuse to sell fish labeled as "organic." However, others, like Wegman's, have permitted the sale of "organic" marketed fish under European Union or Canadian organic certifications.

Seafood snobs may say they "always prefer the taste of wild-caught fish" over the taste of farm-raised fish. Unfortunately, there is no "right answer" for which type of fish is superior, and the answer depends entirely on consumer preference. It also depends on the diet and habits of the fish in question.

Take salmon, for example. Farm-raised salmon is fattier in texture and milder in flavor because the fish is fed a formulated feed regimen. Since it has a higher fat content, this makes salmon a little more forgiving than wild-caught salmon when it comes to cooking. It is harder to overcook because it contains more fat, which makes it better for high-heat cooking than wild-caught salmon. If you're cooking wild-caught fish, avoid cooking it past medium rare. Otherwise, you'll dry the fish out quickly and cause it to become chalky.

Large, predatory fish like tuna and swordfish are often associated with heavy metal accumulation, like mercury. Heavy metals are most likely to be found in these fish species, many of which cannot be grown in farmed conditions because the toxins bioaccumulate throughout the food chain. Both farmed and wild fish can be exposed to mercury because of industrial pollution in lakes, rivers, and other waterways where the fish are farmed or live. Still, the risk is minimal compared to the consumption of large predatory species (via Colorado State University). In addition, early studies of farmed salmon showed higher rates of polychlorinated biphenyls (PCBs) compared to wild-caught salmon, but follow-up studies have not confirmed this differential, notes the Washington State Department of Health.

One emerging issue within farmed fish is the ingestion of microplastics from fishmeal. The human health impact of ingesting these microplastics via farm-raised fish is unknown but potentially nulled by the phasing out of fishmeal in favor of plant-based fish feeds (per Environmental Health News). That being said, there is also little research to indicate that there is a tangible difference between the number of microplastics consumed by wild versus farm-raised fish.