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Fish Farms: What Is Fish Farming and Why Is It Bad?

February 22, 2022

The idea that fish are merely a resource or material for us to make use of couldn’t be further from the truth. Even though we might find it much harder to relate to a salmon than we would to a sheep, a growing body of scientific research demonstrates that fish are complex individuals who have the capacity to experience pain and emotions. 

Based on the fact that fish can suffer, the way they are currently treated is a major issue of moral concern. Right now, tens of billions of fish are held captive in industrial farms around the world. 

What Is Fish Farming? 

Fish farming is the practice of commercially raising fish in a captive environment to be killed and sold for human consumption. Farmed fish are typically mass-reared in overcrowded, unnatural conditions, and their wellbeing is largely ignored. Fish farming is different from capture fishing, which is the practice of catching fish directly from the wild, but both industries are ethically and environmentally problematic. 

Pisciculture or Fish Farming?

Pisciculture is a fancier term for fish farming that has the same meaning: the captive rearing of fish for human consumption.  Pisciculture falls under aquaculture, which also includes the farming of crustaceans, mollusks, seaweed, and other aquatic animals and plants.  

Recent decades have seen a rapid increase in the killing of aquatic animals for food.  In 1970, global seafood and fish production totaled around 64 million tonnes. By 2013, that figure had passed 154 million tonnes. Today, more than half of global seafood production comes from farming.  

Aquaculture takes place on such a massive scale that it is difficult to quantify exactly how many individual lives are taken. Researchers estimate that between 250 and 408 billion farmed aquatic animals are killed per year worldwide. Of these, around 59 to 129 billion individuals are thought to be vertebrates such as fish.

As of 2019, fish belonging to the Cyprinidae (carp) family were the most farmed fish by quantity, accounting for nearly 25 percent of total global farmed seafood production. Other commonly farmed fishes include catfish, tilapia, salmon, and trout. 

What Are the 3 Types of Fish Farming?

While almost all fish farms are factory farms, there is some variation when it comes to the systems of confinement that fish are kept in. 

Cage Systems

Modern cage culture systems are a highly productive form of industrial fish farming, in which groups of fish are kept outdoors in densely packed underwater enclosures. The enclosures, or cages, make use of existing areas of surface water such as rivers or lakes, and are either anchored down or float. Most cage systems are open, letting water move freely through them while the fish are confined and allowing any chemicals or waste from the farm to escape uncontrolled into the surrounding environment. 

Irrigation Ditch or Pond Systems 

Fish raised in these systems are held in an enclosed body of water. Fish are either kept in an irrigation ditch so that their waste products can be used as crop fertilizer, or in a pond where food can be grown for the fish to eat, making the enclosure self-sustaining.  

Integrated Recycling Systems

In integrated recycling systems, also known as aquaponics, fish are confined to plastic tanks inside greenhouses. The nutrient-rich wastewater from the fish tanks is used to grow herbs such as basil and parsley without the use of soil. By absorbing the nutrients, the plants clean the water, allowing the water to be re-used for the fish. Unfortunately, these systems can also introduce E. coli into produce grown using fish wastewater.

Classic Fry Farming

Classic fry farming is the incubation of fish eggs and the rearing of baby fish. Once they are able to survive on their own in the wild, the juvenile fish (known as fry) are set free in a river or stream where they continue to grow. The adult fish are then caught and killed for sport. 

Why Is Fish Farming Bad?

Fish farming is a leading cause of animal suffering. Fish are treated like commodities, rather than individual animals, and even “high-welfare” fish farms do not meet the basic welfare needs of farmed fish. 

One of several problems with pisciculture is that many species of farmed fish are still wild and those that are domesticated have only been so for a relatively short period. For that reason, the majority of individual animals used in the aquaculture industry are ill-suited to life in a captive environment. Atlantic Salmon, for example, would naturally travel for thousands of kilometers but captivity makes this impossible. The rapid recent growth in fish farming also means that scientific study of its effects on different species and the environment is still in its infancy, which makes it harder to develop laws to limit its impact.

As well as making life miserable for billions of sentient beings, as with all animal agriculture fish farming can cause significant environmental damage. The aquaculture industry is not nearly as sustainable as it claims to be. 


While fish farming is often seen as a solution to overfishing, this isn’t necessarily the case. A 2019 study found that fish farming often takes place in addition to capture fishing, rather than instead of it.

Because some farmed species of fish, such as the Atlantic Salmon, are carnivores whose natural diet consists of other fish, pisciculture can actually increase the pressure on wild fish populations. For every pound of flesh produced, a farmed salmon will eat three pounds of feeder fish. Each year, hundreds of billions of individual forage fish (species such as anchovies, sardines, and herring) are taken from the wild, killed, and turned into feed for farmed fish. 

Stocking Density

To maximize production while keeping costs low, fish farms typically keep high numbers of animals in as little space as possible. The impact of stocking density on fish welfare largely depends on the species. Some fish naturally move around in schools and can be negatively affected by low stocking densities, while others suffer from stress, poor health, lower quality of life, and premature death when forced to live in high densities. 

Stocking density can also impact water quality. Keeping too many fish confined in a space results in lower levels of dissolved oxygen, and can affect other aspects of water quality including acidity and levels of carbon dioxide and ammonia.

Parasites and Disease

Many farmed fish are affected by parasites and diseases, sometimes as a result of poor water quality or a stressful environment. As well as being a major animal welfare concern, viruses from fish in underwater factory farms can become a threat to the environment if they infect wild fish populations.

A fish farm with hundreds of thousands of fish living in close confinement creates the ideal conditions for parasites such as sea lice to thrive. While a wild salmon in the ocean might be affected by a small number of sea lice that cling on to him for a short time, a farmed salmon is at risk of being attacked by large numbers of sea lice that will eat the skin away from their head and neck completely.

Ecosystem Impacts

Wild fishes play a vital role in sustaining marine ecosystems when allowed to live freely, but intensive farms that keep unnaturally high numbers of these animals in captivity have numerous negative impacts. These include nutrient pollution, biodiversity loss, and the release of hazardous chemicals into the environment.  

Keeping many fishes in confinement naturally results in a lot of waste. Fecal matter and excess food pellets from fish farms can pollute waterways with nitrogen and phosphorus, and these excess nutrients can cause harmful algal blooms that starve the water of oxygen as they decay. 

Another common problem with pisciculture is that a small percentage of fish are likely to escape from farms that use open cage systems. While this might be good for the fish who get out (although they may not know how to survive in the wild), it isn’t so good for the environment. Farmed fish might prey on, compete with, or spread disease to native wild fish populations. 


The scale of the environmental damage caused by a factory fish farm can vary depending on its location. Many fish farms are sited in bodies of high-quality water. This can make the pollution of surrounding waterways even more harmful than it might be otherwise. 

Genetic Modification

Like other intensively farmed animals, many species of farmed fish have been selectively bred over time to grow quickly and reach unnaturally large sizes. Some fish populations are biologically manipulated in other ways too. A group of tilapias, for example, might be fed hormones when they are young to turn any females into males so that they will grow faster, while a group of salmon might be made all-female for higher carcass quality. 

In recent years, the aquaculture industry has also been experimenting with the use of gene-editing technology. In 2015, transgenic farmed salmon containing DNA from two other fish species became the first genetically modified animals to be authorized in the U.S. as safe for humans to eat. The commercial killing of these fish, which grow twice as fast as their unmodified counterparts, started in 2021. 


The label on a packet of fish is largely designed to sell animal flesh and is unlikely to give you an accurate picture of how that animal lived and died. As with any other animal product,  there is a concerning lack of enforcement when it comes to how fish is labeled. In some cases, farmed Atlantic salmon has been mislabeled as “wild,” “Alaskan,” or “Pacific.” If someone tries to sell you wild Atlantic salmon, you are being lied to. There are no wild Atlantic salmon in the US market.

Inhumane Slaughter Methods 

Fish are not included in the Humane Methods of Slaughter Act, the only piece of federal legislation that exists to regulate the treatment of animals at the time of slaughter.  As a result, the majority of fish are not stunned (rendered unconscious or unable to feel pain) before being killed, leaving them fully alert and awake during the slaughter process. 

One common method used to kill fish is asphyxiation in the air, which involves the fish being taken out of the water so that their gills collapse and they die from a lack of oxygen. Asphyxiation (suffocation) is very distressing for fish, as it would be for any animal, and they frequently try desperately to escape. Other inhumane methods of slaughter include asphyxiation on ice, live chilling, bleeding, and electrocution. 

Can Fish Farming Be Better?

The fish farming industry could do a lot more to reduce animal suffering and better protect the environment. However, like any other form of raising animals for food, fish farming ultimately relies on the killing of sentient beings who want to live. It is therefore inherently harmful.


Although often seen as better than meat and dairy production, fish farming harms the environment and causes billions of individual animals to suffer. Choosing plant-based alternatives to conventional fish products can help to build a future where all carp, catfish, tilapia, and salmon live free in the wild where they belong.