Fish Suffer up to 22 Minutes of Intense Pain When Taken Out of Water

What if the fish on your plate endured nearly half an hour of intense, conscious pain before it died? It’s a deeply unsettling question, but one that groundbreaking research is forcing us to confront. For decades, the debate has centered on if fish feel pain. Now, by moving beyond that question to quantify how much they can suffer, scientists are shedding a harsh light on a common and legal practice in the global food industry. A new framework for measuring animal welfare is challenging us to look closer at the journey from water to plate, and the findings are difficult to ignore.

A Startling New Metric for an Age-Old Practice

A study published this year in Scientific Reports puts a stark, quantifiable number on this suffering. In a deep analysis led by welfare scientists Cynthia Schuck-Paim and Wladimir J. Alonso, researchers investigated one of the most common slaughter methods for farmed fish: asphyxiation, or suffocation in open air. By synthesizing decades of existing physiological and behavioral data, they concluded that a rainbow trout can experience between 1.9 and 21.7 minutes of moderate to intense pain and distress from the moment it is pulled from the water until it loses consciousness. The “up to 22 minutes” figure represents the upper end of this scientifically derived range.

This calculation is the result of a powerful new tool called the Welfare Footprint Framework (WFF). The framework’s mission is to move beyond qualitative statements of concern and instead quantify animal welfare impacts using a “biologically meaningful, relatable and comparable metric.” It does this by carefully assessing the intensity and, crucially, the duration of an animal’s suffering.

When applied to an industrial scale, the numbers become even more staggering. The researchers calculated that the practice of asphyxiation results in an average of 24 minutes of moderate to extreme pain for every single kilogram of fish filet produced. In certain conditions, such as with larger fish in colder temperatures which prolong the dying process, that figure can rise to over an hour of pain per kilogram of product on a supermarket shelf. For the first time, the abstract concept of suffering has been translated into a tangible metric we can all understand.

What Science Tells Us About Fish Suffering

This leads to a fundamental question: can a fish actually feel pain and suffer? For years, many have assumed that a fish thrashing on a deck is just a simple, mindless reflex. But a growing body of science reveals a much more complex and conscious experience.

The evidence starts with biology. Fish have specialized nerve endings called nociceptors, which are designed to detect painful stimuli and are concentrated in sensitive areas like the head and mouth. When these are triggered, pain signals don’t just cause a knee-jerk reaction; they travel to parts of the brain involved in processing memories and emotions. Even more convincingly, fish produce their own natural painkillers, just like humans do. When scientists give injured fish a pain reliever like morphine, their complex pain-related behaviors stop. This pain relief system wouldn’t exist if fish didn’t have pain to relieve in the first place.

This biology is matched by fascinating behaviors that show a conscious mind at work:

• They seek out pain relief: In one key study, injured zebrafish were given a choice: stay in their preferred, plant-filled environment, or move to a barren tank that was infused with a painkiller. The fish chose to leave their home for the boring tank to get relief, a sophisticated decision that points to a conscious desire to stop suffering.
• Pain distracts them and makes them ignore danger: Rainbow trout are naturally afraid of new things. But when injured, they became so focused on their pain that they didn’t react with their usual fear to a brightly colored Lego block placed in their tank. This shows that pain was dominating their attention, a hallmark of a conscious experience.
• They remember painful events and feel fear: In another experiment, a light was turned on just before a net was plunged into the tank. The fish quickly learned to associate the light with the threat and would flee as soon as the light appeared, showing they could remember, anticipate, and feel fear.

While some skeptics point out that fish lack a neocortex—the part of the human brain tied to higher consciousness—the evidence suggests this may not matter. Many scientists now believe different brain structures can produce similar feelings. Because of this overwhelming evidence, most welfare experts have adopted a common-sense approach: the most responsible and ethical path is to act on the basis that fish are indeed capable of suffering, and to treat them accordingly.

Not All Deaths Are Created Equal

Understanding that fish can suffer makes the method of their death critically important. For a fish, dying by asphyxiation—the practice analyzed in the “22 minutes” study—is a physiologically brutal process. Out of water, their delicate, feather-like gills collapse and stick together, making breathing impossible. They can’t get oxygen in, but just as critically, they can’t expel carbon dioxide. This CO2 builds up in their blood, creating a painful, burning sensation that stimulates their nociceptive system and triggers reflexive gasping. The entire process is a prolonged state of panic and exhaustion that ends only when the fish finally loses consciousness.

This is not the only common method considered inhumane by welfare experts. Many fish, such as sea bass and sea bream, are killed by being placed in an ice slurry. While this may seem less violent, it is also a slow and highly stressful death that can last up to 40 minutes. A major welfare concern with this method is that the extreme cold can paralyze the fish long before they lose consciousness, making them appear calm and still to an observer while they continue to suffer internally.

Fortunately, humane alternatives exist. The two most widely accepted are:

• Percussive Stunning: A swift, powerful, and accurate blow to the head that causes immediate and irreversible brain death.
• Electrical Stunning: Using an electrical current to pass through the fish’s brain, inducing an immediate seizure and rendering it instantly unconscious.

However, these methods are not simple silver bullets. Their effectiveness depends entirely on correct application, creating a significant “implementation gap” between their potential in a lab and their performance on a high-speed processing line. A manual percussive stun can easily miss its mark, while automated systems must be perfectly calibrated for fish size. The risks with electrical stunning are even greater. An incorrect current or frequency can fail to induce unconsciousness and instead paralyze the fish, leaving it fully aware and able to feel pain but unable to move or show it—an exceptionally cruel outcome. The effectiveness is notoriously sensitive to factors like fish size, water temperature, and equipment maintenance, making consistent, humane application a major industrial challenge.

How Market and Policy Can Drive Change

Given the complexities and costs of upgrading to humane methods, why would a commercial producer make the switch? The motivation comes not just from ethics, but from a powerful combination of economics, market pressure, and consumer demand.

First, there is a strong business case rooted in product quality. A significant body of research shows that the intense physiological stress from a prolonged and inhumane death negatively impacts the fish’s flesh. It can lead to a soft or mushy texture, bruising, and a shorter shelf-life on the grocery store counter. Conversely, a quick and low-stress death through effective stunning results in a firmer, higher-quality product that can command a better price, especially in high-end markets.

Perhaps the most powerful driver of change is market access. A growing number of major food retailers and restaurant chains, particularly in the United Kingdom and Europe, have established strict animal welfare standards as part of their procurement policies.

For aquaculture producers, failing to use humane slaughter methods can mean being locked out of these lucrative markets. This pressure from corporate buyers effectively turns animal welfare from a ‘nice-to-have’ into a critical business requirement.

These corporate policies are especially important because government regulations vary so widely across the globe. The level of protection a fish receives often depends more on its species and where it is farmed than on a universal ethical standard. This “patchwork of protection” means that in many regions, the standards set by retailers are far more influential than local laws.

Finally, consumer voices are beginning to create ripples. A recent survey in several European countries found that 83% of consumers support the use of stunning before slaughter, and 80% of those who buy fish like sea bass and sea bream would be willing to pay a small premium for a humanely slaughtered product. While this premium may be modest, it sends a clear signal to the industry: customers are paying attention, and they are willing to reward producers who prioritize compassion.

A Turning Point for the Fish on Our Plates

It’s one thing to debate whether fish can feel pain; it’s another thing entirely to see a number like “22 minutes” attached to their final moments. That kind of stark data is hard to ignore, and it feels like it’s pushing the entire seafood industry toward a real turning point. The conversation is finally shifting away from philosophical arguments and toward practical questions. The new focus is all about finding humane solutions that can actually work in the real world, on a massive, industrial scale.

And you can already see the wheels of that change starting to turn, mostly driven by money, not just morals. Huge international retailers are starting to demand higher welfare standards from their suppliers, which is a powerful incentive to clean things up. At the same time, you’ve got dedicated scientists and non-profits working in the trenches to close that tricky gap between what works in a perfect lab and what holds up on a busy processing line. They’re digging into the research and sometimes even helping producers foot the bill for new equipment, all to make the switch to better practices a little less painful for everyone involved.

Ultimately, what all this really points to is a new chapter in accountability. For a long time, the journey fish take to our plates has been mostly out of sight and out of mind. Information like this—as unsettling as it is—drags it out into the open. It’s not about shaming anyone, but about a growing awareness of where our food comes from. For fish, one of the most important food sources on the planet, that story is finally, slowly, coming into the light.

Source:

1. Schuck-Paim, C., Alonso, W. J., Pereira, P. A., Saraiva, J. L., Cerqueira, M., Chiang, C., & Sneddon, L. U. (2025). Quantifying the welfare impact of air asphyxia in rainbow trout slaughter for policy and practice. Scientific Reports, 15(1). https://doi.org/10.1038/s41598-025-04272-1