Fish experience excruciating pain during slaughter, a new study confirms
New research confirms fish experience prolonged and severe pain during slaughter, raising urgent questions about animal welfare in the seafood industry.
It is widely known that other animals farmed and killed in our current food system can feel pain and suffering. However, such acknowledgement is rarely given to fish or other aquatic species.
Now, researchers have confirmed that fish can experience intense pain when subjected to a common slaughter method known as “air asphyxia”, in a study that could encourage consumers to reconsider their eating choices.
Scientists at the Welfare Footprint Institute found that the average rainbow trout experiences between 1.9 and 21.7 minutes of moderate to excruciating pain when suffocated in air on ice.
This intensity of the pain can depend on factors such as the weight of the fish and the water temperature, with scientists finding that fish suffer for about 24 minutes per kilogram. In some instances, fish could experience over one hour per kilogram of pain, the study authors wrote.
When fish are pulled from water by nets or hooks and left to die in air they experience a slow, stressful decline marked by frantic gasping as oxygen levels plummet and carbon dioxide builds up, according to the study.
Scientists estimate that fish can remain in this panicked, painful state for up to 25 minutes before losing consciousness. The first 10 minutes of that ordeal can involve pain that researchers categorise as disabling, hurtful, or excruciating.
Each year, up to 2.2 trillion wild fish are caught globally, with around half being ground into feed for other farmed animals. Alongside them, an estimated 171 billion farmed fish are raised and slaughtered.
Despite the suffering it causes, air asphyxia remains the most common slaughter method for fish. Some are killed by chilling in ice or an ice slurry, methods often perceived as more humane. But according to researchers, these alternatives may simply prolong the time it takes for the fish to lose consciousness, extending rather than easing their suffering.
Alternative slaughter methods to air asphyxia include gassing with carbon dioxide or cutting the gills without stunning. Some fish are processed while still alive and conscious.
Photo: Amy Jones/Moving Animals
In light of this latest study, the researchers are calling for air asphyxia to be banned, and for stunning methods to be implemented across the fishing industry.
“Pain and distress from asphyxia in fish can be potentially mitigated by stunning methods that induce rapid loss of consciousness,” they wrote in their study. “For stunning to be considered humane and effective, pre-slaughter handling must be minimised and the animal must become unconscious immediately after stunning, a state that must persist until death.”
However, animal advocates argue that does not go far enough to protect fish from pain and suffering.
“In 2025 the scientific consensus toward animals is shifting, and with it, our moral obligations,” said Elizabeth Novogratz, the Founder and President of Species Unite. “This latest study adds to the ample body of evidence that proves fish can feel pain and suffer, from showing stress behaviors when injured, detecting harmful stimuli, and exhibiting nervous and physiological responses consistent with pain. To eliminate fish suffering properly, and prevent the slaughter of trillions of sentient beings, we must move towards a plant-based food system.”
Research has shown that many nonhuman animals possess not only the neurological structures needed to process pain, but also the capacity for emotional suffering, fear, and even empathy. Pigs have been shown to exhibit signs of emotional contagion, responding with distress to the squeals of their peers. Chickens can anticipate pain and show avoidance behavior. As evidenced in this study, fish display complex pain responses and learning behavior, while cephalopods like octopuses can experience both physical and psychological distress.
But despite mounting scientific evidence, legal protections and rights for animals remain limited. In many countries, farmed fish are excluded from humane slaughter regulations, which is particularly alarming when viewed alongside this recent study. Billions of chickens are raised in horrific environments where basic welfare is ignored. And countless animals used in laboratory experiments are still subjected to painful procedures.
“As science dismantles the myth that animals don’t suffer, the question is no longer whether they feel pain, but whether we’re willing to take action based on that knowledge,” said Novogratz. “With up to 6.5 billion animals killed for food every day, the answer, so far, is a resounding ‘no’.”
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