Society for the Advancement of Animal Wellbeing

- Protecting Animals and Conserving the Environment

Fish farming - silent screams

The treatment of these marine animals could actually be considered worse than the treatment of factory farmed animals. The reason for this is that the current thinking is that fish do not feel pain; this of course is scientifically not true. Just because fish do not express pain in a way visible or audible to humans it does not mean they do not feel pain. In fact fish do communicate using a variety of low frequency sounds including clicks, buzzes, sobs and screams all of which may seem silent to human ears.

We will now present research conducted by experts that conclusively show that fish do in fact feel pain, stress and anxiety just like any other vertebrae like your cats and dogs or even other primates. In fact Dr. Donald Broom Professor of Animal Welfare and advisor to the British government has said “The scientific literature is quite clear. Anatomically, physiologically and biologically, the pain system in fish is virtually the same as in birds and mammals.”

So what is the “pain system” in fish? Just like humans and other mammals, fish have nerve endings and pain receptors near the surface of the skin called nociceptors. When the skin is damaged a chemical called bradykinin is released this causes the nerve to send a message which releases a second neurotransmitter called “substance P” which in turn sends a message up the spine to the brain which feels the sensation of pain.

These chemicals that transmit pain are found in all mammals, birds, fish and frogs. Fish also produce chemicals called endorphins which block the feeling of pain; this is the exact same chemical that is found in humans. In fact morphine which is a painkiller has the same effect of blocking pain transmission in humans as it does in fish.

Similarly according to Dr. Andrew Rowan adjunct professor at the Tufts University School of Veterinary Medicine, the fish’s brain also has receptors for the drug valium which is used for reducing anxiety in humans, thus it can be concluded that fish also experience anxiety and stress.

According to research conducted By Dr. Culum Brown at Macquarie University, fish have the cognitive abilities greater than or equal to primates and elephants, not only can they recognize individuals but they can also use tools, learn and teach as well as form complex and intricate social relationships. Research has also shown that fish can anticipate future adverse events and can even be trained to tell time.

Studies at the Roslin Institute in Edinburgh showed that fish may rock back and forth when they feel physical and mental pain, this is similar to the behavior seen in deeply shocked human or factory farmed animals. Deep sea divers have also witnessed fish that follow the divers and enjoy being petted much like a cat or dog.

Breeding and reproduction

Every year literally billions of fish are brutally killed with out stunning in some cases the fish are eaten or cooked alive in accordance with culinary traditions in certain parts of the world like Japan and China.

The delicacy called ying-yang fish, consists of a fish that has half of its body fried but its head is protected, he is served still alive and aware with a vegetable covering his or her eyes so that he will not move when his half fried body is cut, picked at and eaten. Even factory farmed animals are not treated in this way.

In 2003 the UN’s Food and Agriculture Organization estimated that worldwide fish production was 132.5 million metric tons. Of this amount 42 million tons were from fish factory farms known as aqua culture whilst 90 million tons were captured in drift nets or by trawling. In 2005 the total went up to 142 million tons; unlike land animals the number of actual lives taken is not recorded instead they are measured by weight, so it is hard to know the actual numbers of lives taken but the estimates are higher than the numbers of chickens killed and eaten each year.

We will now take a deeper look at the inhumane conditions and methodologies of fish farming. It is important to note that practices vary according to the species of fish and the country. Production of baby fish known as fry or fingerlings is the first step.

For this a breeding stock of male and female fish are kept. The female will be periodically felt and palpated in order to check if the egg mass is free. This continuous checking is very stressful for the fish as they are handled roughly and pulled out of the water. If the egg mass is free, the eggs are then squeezed out of the mother fish through the genital papilla, this is inherently painful and sore. Alternatively a jet of water may be shot into the body cavity in order to flush out the eggs or the eggs may simply be cut out with a knife. After this the female will usually be killed and sold at market.

Next the males are milked through squeezing, this is extremely agonizing and distressing to the fish who may be milked up to 5 times before also being slaughtered. The eggs and semen are mixed and kept in temperature controlled conditions.

The new born baby hatchlings are then fed and when they get to the right size which is 4 to 7 inches for Salmon they are subsequently starved and the transported to be intensively raised in factory farms. The method of handling and the transport itself damages the infants’ fragile and developing bodies. The reason for starving them is so they do not defecate during transport and thus die from the toxic conditions.

Fish factory farms

Fish farms are of two types, in-land farms and sea farms. In-land farms use concrete tanks measuring up to 35 meters in length; the light and food are tightly controlled and monitored.

The farms at sea consist of 70 meter diameter cages floating along the shore line at the estuaries of rivers. The fish are packed tight and confined in these cages each of which may contain more than 50,000 salmon or 270,000 trout. That’s similar to having a 2.5 foot salmon in one bathtub of water. Such ridiculous and suffocating stocking densities come with a host of problems.

Other sea animals such as eels, prawn and tuna are also factory farmed. Tuna in the wild can live for up to 40 years and swim 70 km per hour however in the farms 2,000 tuna are confined to a 30 meter tank. Wild Salmon are migratory and are used to swimming across oceans, in such confinement they usually go insane and repetitively swim in circles much like the repetitive behavior of zoo animals or factory farmed pigs and cows. The claustrophobic confinement even causes some fish to die from stress.  These sensitive fish may also become cannibalistic and start fighting and biting each other. They also swim in to one another as well as in to the sides of the tank or cage thus sustaining injuries.

Also the massive amounts of fecal and nitrogen based waste causes many problems due to poor hygiene. Such conditions include kidney and pancreas infections, cancers, furunculosis, vibriosis and sea lice. Disease, stress, illness and deformities will kill anywhere from 20% to 50% of the animals before they reach slaughter weight.

Sea lice are a particularly bad problem in fish farms (sea image on the left). A normal wild fish may have up to 5 lice on its body but the unsanitary conditions on farms mean that a single fish can easily have more than 500 lice some even have up to 3,000. These lice can eat the entire fish alive from the outside in. Many fish have exposed bone or skulls from where the parasites have eaten through the flesh.

To treat this, the farmers use hazardous chemicals such as organophosphates, hydrogen peroxide, formalin or malachite green. These chemicals are also dangerous to human health if consumed in significant amounts.

Salmon also suffer from infectious Salmon anemia (ISA) which causes agonizing internal bleeding of the fish, and there is some evidence that this can also affect humans. Furthermore 40% of the fish may suffer from blindness due to cataracts.

The huge amount of excrement from fish farms also pollutes and destroys the local environment and greatly effects the local wild fish populations. In the Scottish west highlands alone fish farms produce 11,000 tons of waste per year which is the same as the amount produced by a city of 10 million people. This waste also causes vegetation to grow and is also known to cause algal blooms and dead zones.

For all of these problems; more and more chemicals including herbicides, disinfectants, antibiotics, hormones and a host of other chemicals are given to the fish which makes them even more ill.

The fish, many of which are herbivores may be fed a diet of other dead fish high in oils and fats in attempt to fatten them up and thus make them more profitable, this is similar to feeding grass eating cows a diet of other animals and so often causes the spread of disease.  Even for the fish that are carnivores the fish farming process is extremely inefficient. For certain salmon 5 kg of fish must be fed to them in order to yield 1 kg of flesh. So this also negates the argument that factory farms are allowing wild fish stocks to recuperate.

Most farms also operate a system of “grading” to separate the smaller fish from the larger ones. This process involves a machine that sucks them up through a pipe and then shoots them over a grill with bars that have different gap sizes; the fish fall though the appropriate gaps and then are flushed in to a separate tank. This process may occur up to 5 times during their life and apart from anxiety also causes damage to the delicate scales and gills as well as other physical injuries such as bruises and broken bones.

Biotechnology and genetic modification is also widely practiced to get the fish to grow fatter and faster. Therefore their systems and internal organs can not keep up with the exaggerated growth and they may suffer problems similar to broiler chickens, turkeys and other factory farmed animals.

Additionally Salmon are fed pigments to make the color of the flesh pink and thus more appealing to consumers. However pigments commonly used such as canthaxanthin are known to be cancer causing agents. The fish may also have a number of mutilations carried out on them for identification purposes; these include clipping of fins and the use of tags which pierce the skin and flesh.     


Transport and slaughter 

When the fish reach the required weight they will be transported for slaughter. Prior to transport they will be starved for 2 to 10 days this is to ensure that they do not contaminate the transport water.

The fish will be sucked up through a vacuum machine and dumped into the transport vehicle or alternatively nets will be used, both methods are extremely upsetting for these beings and also cause physical injuries to their bodies.

Being on a moving truck in darkness, confined and starving with low oxygen levels is too much for them and some fish will inevitably die from these appalling conditions.


The slaughter of fish must be considered the most crude and cruel amongst all. In reality there is little regulation and stunning is not required. For larger fish they will first be hit on the head with a wooden club called a “priest” the gills, essentially the fish’s lungs will be cut in order to bleed them out.

Some fish may be stunned by immersion in carbon dioxide saturated water. Although this is meant to be humane, in reality it is torture, the fish once submerged writhe and thrash in agony trying to escape. They are rendered immobile after 30 seconds however it takes 4 to 5 minutes for them to lose consciousness so many are still fully conscious when being slaughtered and having their gills cut open and their internal organs removed.

On many occasions the fish have their gills cut with out any prior stunning, this will no doubt cause extreme pain and trauma to the animal as can be seen by their attempt to escape and their consequent convulsions.

Other methods including passing an electrical current through the holding tank, this often causes spinal fractures and hemorrhaging and may have to be repeated if the current was insufficient.

Another common practice especially with smaller fish is to just let them suffocate also know as asphyxiation. The water is simple drained away and the fish are left to suffocate in air.

Another cruel practice which is also very widely used is asphyxiation on ice, this is when the fish are packed fully alive and conscious in to bins containing ice, they are left to suffocate and freeze to death. Studies have shown that fish killed by suffocation in ice can still feel what is happening to them 15 minutes after they have been buried alive.



It is clear that fish have feelings and are fully sentient. So how can we stop this cruelty, the simple answer is to adopt a compassionate and healthy plant based diet free from any animal products. Many alternatives exist such as faux fish and veggie sushi which taste great but do not involve the cruel torture of marine beings nor do they burden the resources and environment of our beautiful planet. For more information on fish farming please visit

Click here to find out how you can help!

Read more on factory farming or visit the section on other issues regarding animals here.


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