What Fish Farming Really Means for the Environment, Animals and People

Despite the seafood industry’s claims, eating fish may not be as healthy or sustainable as consumers have been led to believe.

Various fish in the water

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With growing concerns for both environmental sustainability and animal welfare, consumers in the United States are increasingly opting for diets that are free of animal products. Definitions can be inconsistent, however, and some self-identified vegetarians actually follow a pescatarian diet, abstaining from all meat besides fish. But why are fish not seen as meat? Fish often occupy a grey area for consumers, possibly because it can be difficult to sympathize with or prioritize the welfare of animals so vastly different from ourselves.

Research indicates that consumers do care about where the fish they consume comes from. Yet even though fish farming is touted as a more sustainable solution to wild fisheries, evidence suggests that both methods have their share of problems. For instance, wild capture most notably results in bycatch and the death of countless non-target species.

Let’s look into the reality of fish farming, and how it harms animals and the environment — and why eating fish might not be as healthy or sustainable as many consumers believe.

The Rapid Rise of the Fish Farming Industry

The terms ”pisciculture” and “fish farming” refer to the same practice: captive breeding and rearing of fish for human consumption.

The industry is growing. Fish farming has seen exponential growth and now surpasses wild capture fishing numbers, which have remained relatively stable over the past few decades. Recent data shows that wild-caught fish amounted to about 91 million metric tons globally in 2020, while industrial production was responsible for over 120 million metric tons.

Farmed fish currently account for over 50 percent of all farmed invertebrates. Fish farming is not especially different from other forms of factory farming: animals are bred in mass quantities, raised in enclosed, unnatural conditions and ultimately slaughtered before being sold as food.

When Did Fish Farming Begin?

Fish farming of any kind dates as far back as 2,500 years ago, when Chinese farmers began raising carp.

Industrial fish farming, however, is a far more recent invention. It got its start during the Industrial Revolution and became increasingly popular starting in the 1950s.

How Does Fish Farming Work?

As global demand for fish products grows, fish farming has followed a similar trajectory to other types of factory farming, rapidly becoming more industrialized and consolidated.

Even though both marine and freshwater fish are farmed, some of the details differ. In both cases, the fish are bred for fast growth over a short period — and are then harvested and killed. Different systems are used for fish farming, depending on the species of fish and the desired product outcome, all of which foster unnatural living conditions for fish.

Cage Systems

In cage systems, fish are densely packed in underwater cages made of mesh or netting that are either anchored or free-floating in existing rivers, lakes and oceans. Because water flows freely through these cages, chemicals or waste from surrounding industry flows through as well, and any contained fish are unable to disperse. Fish also commonly experience stress and injuries from the crowding typical to cage systems.

Irrigation Ditch or Pond Systems

Irrigation ditches are usually used for smaller-scale operations. A series of interconnected channels and ditches are used to revert water from natural sources, which allows fish waste to be used as crop fertilizer. On a larger scale, fish food (like algae) is grown within the pond, allowing the pond to be self-sustaining. While this might sound good in theory, high temperatures and low oxygen levels in these setups can cause disease outbreaks for fish.

Integrated Recycling Systems

Integrated recycling systems describe a setup in which fish are confined to plastic tubs alongside hydroponic beds inside of a larger greenhouse. The nutrient-rich wastewater from the tubs is circulated and used to grow various crops (typically herbs) in the hydroponic beds. In turn, the crops clean the water through nutrient absorption and it is reused by the fish. While this might sound sustainable in theory, these systems have been found to introduce E. coli from the fish wastewater.

Classic Fry Farming

In classic fry farming systems, also known as “flow-through systems,” fish eggs are incubated and baby fish are reared before they are released into rivers or streams. These juvenile fish, called fry, are later caught or killed for sport as adults.

Is Fish Farming the Same as Aquaculture?

Fish farming refers exclusively to the breeding and harvesting of fish, while aquaculture is the breeding and harvesting of all aquatic animals, like octopus, shrimp and even plants, like seaweed.

Industrial Fish Operations Are Just Like Factory Farms

Fish Are Packed Into Small Spaces

Farmed fish are densely packed in small spaces in order to maximize production. The negative consequences of high stocking density present differently depending on the life stage or species of a fish. That said, conditions are generally highly stressful and can cause infections, aggressive encounters and food competition. Furthermore, high stocking density also reduces water quality and alters the levels of dissolved oxygen, acidity, carbon dioxide and ammonia.

Parasites and Disease Spread Rapidly in Tight Quarters

The close quarters and increased contact of farmed fish often allow parasites and diseases to flourish. On top of this, there are no predators to consume dead or dying fish, and infected fish are often not removed promptly from their enclosures, which can cause additional risk to other captive fish. Parasites and diseases run the risk of infecting wild fish populations as well; many  cage systems exist in open waters, meaning any tainted water flows right out into the surrounding waters.

Fish Farming Harms the Environment

Just like most other factory farms, fish farming is responsible for a massive amount of waste, which causes water pollution when released. Both fecal matter and uneaten food from fish farms pollute surrounding waters with excess nitrogen and phosphorus that can lead to algal blooms, depriving the water of oxygen.

The specific site of a fish farm will dictate the scope of its environmental, social and economic impacts. Cage systems that sit in existing and open waters are more likely to spread parasites, disease and fish waste into surrounding waters. Most fish farms are located near the shore, which can also cause conflicts with local communities who are impacted environmentally and socially by their presence.

There Are No Fish Welfare Provisions

The Humane Methods of Slaughter Act, the only federal legislation that covers the killing of farmed animals, does not cover the slaughter of farmed fish. Because welfare is not a consideration at the time of death, farmed fish are most commonly subjected to death by asphyxiation, either in the air or on ice. This can take up to several hours, during which fish   show signs of distress before dying.

Genetic Modification

The farmed fish industry does rely on genetic engineering to develop quick-growing breeds. Most genetic modification of fish is done in the salmon sector, which boasts the most established and advanced breeding techniques. In recent years, the United States Food & Drug Administration (FDA) approved a type of fish called AquAdvantage, a genetically engineered salmon designed to reach growth markers more rapidly with the help of growth hormones from a different species. The FDA determined there were no safety risks to consumers posed by the genetically engineered fish.

Although the USDA regulates labeling of such genetically modified fish, this merely indicates that the product has been bioengineered, and does not provide information on the living conditions or welfare of the animal. Animal welfare labeling can be difficult to enforce and may not always be accurate.

Are Farmed Fish Healthy?

Seafood companies are primarily concerned with maximizing profit and efficiency. Yet these shortcuts can cause long-term harm for short-term gains.


Fish farms are often so crowded that when one fish gets sick, disease spreads to many others, and antibiotics are administered generously and, in many countries, routinely in hopes of minimizing disease spread before it starts. Consuming food laden with antibiotic resistant bacteria is contributing to rising rates of antibiotic resistance in humans.


Although pesticides are effective at eradicating targeted pests, they can sometimes be harmful to other organisms, especially when applied without oversight or management, as is more common outside the U.S. Beyond the immediate food chain, pesticides can spread quickly to the rest of the marine environment, as well as to birds that prey on fish.


One of the most common chemicals found in fish is mercury, which can cause a variety of neurological issues when consumed in high doses.

Is Fish Consumption Increasing?

Despite rising concern about factory farming and animal welfare, fish consumption is actually on the rise. The fish farming industry is growing at a rate of almost six percent annually. This amounts to somewhere between 78 to 171 billion individual fish farmed and slaughtered each year — higher than the number of farmed birds, hogs and cattle killed for food each year, combined. Animal welfare is not the only impact of the growing fish farming industry; environmental sustainability is also on the decline. The Food and Agriculture Organization of the United Nations estimates that unsustainable fish stocks have grown from 10 percent to 35 percent since 1971.

Are Fish Protected by Animal Welfare Laws?

The only federal legislation that governs the actual slaughter of farmed animals does not apply to fish. As such, the vast majority of fish are not rendered unconscious before slaughter. Additionally, the Animal Welfare Act is primarily focused on warm-blooded animals and excludes most cold-blooded marine life. On the state level, many states even explicitly exclude fish from their definition of animals. It is also important to note that countries with zero animal welfare legislation produce about 70 percent of farmed fish worldwide.

How Does Fish Farming Affect the Environment?

Fish farming is not nearly as sustainable as the public is led to believe; its environmental impact is massive. There are a number of ways that fish farming negatively impacts local environments, beyond the obvious polluting of natural waterways and harming local marine life.

Fish Food

Farmed fish include various species of carnivorous fish that must consume other feeder fish. Hundreds of billions of fish, mostly smaller species like anchovies, sardines and herring, are taken from the wild to become feed for farmed fish — in much higher numbers than they would be consumed in nature or even by small-scale fisherman.

What Happens to Soil

Soil quality is a major factor in developing a new fish farm. However, at the end of the farm’s lifecycle, the soil has gone through a complete transformation and is an ecological mess. The soil surrounding the farm often becomes hypersaline, acidic and eroded — and essentially becomes useless as fish and water waste seep into the surrounding land.

Pollution of Waterways and Water Supply

Fish farming uses many chemicals. The combination of fertilizers, antibiotics and pesticides can make the water runoff from fish farms highly toxic. This water flows into local waterways and eventually back into the ocean, polluting both marine ecosystems and water for human consumption along the way.

Spread of Sea Lice

Farmed salmon are particularly prone to infection from sea lice, which find their way beyond the confinement of the fish farms and into natural marine habitats, infecting native and wild populations, causing death and even potential species extinction.


Introducing a new or invasive species into a foreign ecosystem can cause catastrophic damages; the new species competes with native species for food and space, can introduce new pathogens and can even rework the entire food chain. Additionally, without natural predators, invasive species thrive, eliminating the possibility that the ecosystem will return to its natural state.

Can Fish Feel Pain?

Researchers have studied whether fish feel pain and concluded that although fish do not have the same region of the brain that processes pain in humans (the neocortex), there is evidence that these creatures do experience pain. In fact, even fishing industry experts acknowledge that fish feel pain. They not only recoil from painful stimuli but have been shown to avoid previous locations associated with pain.

Yet because there are so few regulations that address welfare in the industry, fish often experience worse living conditions than other farmed species. These conditions have even been shown to lead to high levels of stress and depression. The different ways they are killed can also inflict unnecessary pain and suffering in their final moments.

What’s Better, Farmed Fish or Wild Fish?

Both fish farming and wild capture are detrimental to marine life and larger ecosystems in various ways.

Industrial fishing practices destroy ecosystems and kill countless animals. Industrial fish farming practices are not just killing billions of fish every single year, but also polluting waterways and local ecosystems.

The Bottom Line

Although many people believe fish farming and a pescatarian diet are more sustainable than eating meat, the evidence suggests replacing beef with fish may just involve trading one set of harmful impacts for another.

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