How to Kill a Fish

Most of the fish we eat die by asphyxiation. But there’s a better way, both for the fish and those who eat them.

How did the last fish you ate die? If you don’t already know, then I’ve got some bad news: the most likely answer is that it asphyxiated. Slowly.


While a few species of fish are sometimes killed in kinder ways, the vast majority of those that end up on American plates are pulled from the water and thrown either on ice or left to gasp in air. This is a long and brutal process. Sea bass put in an ice slurry take five minutes to lose consciousness; carp keep breathing for almost an hour in an ice slurry and five hours if out of the water entirely.

If the harvesters go another route, it’s generally either live gutting or slow poisoning in water saturated with carbon dioxide. Whether you want to semantically differentiate a fish’s physical suffering from mammalian “pain” (an argument that biologists, by and large, have agreed to drop), violent escape attempts and biological markers like cortisol and lactic acid leave no doubt that these are terrible ways to die.

Andrew Tsui is intent on making me feel the full moral weight of that suffering. A government health-care lawyer with a lifetime passion for sportfishing, he’s on a journey to change the way Americans—the grass-fed-beef types, anyway—kill and enjoy our aquatic meat.

“I want you to kill one,” he tells me. “Let’s do it the old-fashioned way.”

We’re sitting in the driveway of this corner colonial in a tony D.C. suburb, an unexpected place to learn a lesson about fish slaughter. Tsui himself is a study in contrasts; as we chat, he segues smoothly from a gourmand’s soliloquy on the cultural meaning of food to expletive-laden anecdotes about a job he got after college as a “boat bitch” with a commercial tuna crew.

Tsui pulls a flopping trout from a cooler of water in the back of his truck and drops it in a white plastic bucket with some ice. “This is your buddy,” he says, passing me the handle. The trout’s thrashing makes the bucket sway. We stand around for a while, watching the fish alternate between gasping helplessly and contorting its entire body so violently the bucket’s bottom thunks against the asphalt. Wanting to give the death some gravitas, I pull out my phone and film for a few seconds. It’s the middle of summer, 97 degrees outside, and it’s so humid I leave sweat prints on my screen. After ten uncomfortable minutes, red seeps into the trout’s white belly, internal hemorrhaging from suffocation.

The fish lies upside down in a puddle of melted ice. Andrew squats down and lifts it by the gills to check if it’s dead. It thrashes weakly. He drops it back into the pail and heads over to his big white pickup truck; the bed will serve as our makeshift killing floor, where he’s promised to show me a kinder, gorier death.

Ike jime is a traditional Japanese method of slaughter that results in better-tasting and longer-lasting meat. It’s nearly impossible to find commercial fish in the US that have been killed with the technique, which is the main reason why high-end sushi restaurants often fly their fish in from the Tsukiji Fish Market in Tokyo. Tsui sees that gap in the market as an opportunity for local producers to sell fresh-caught sashimi-grade fish from the country it will be eaten in.

There are some signs that momentum is gathering: a few French fishermen have picked up the technique in the past few years, to the delight of several Michelin-starred restaurants. And this last season, a group of fishers in Washington state tried it out, to rave reviews from local chefs. A few restaurants in the US have begun using it to kill their own fish; there’s even an app for sportfishers to learn the best way to kill each species using ike jime.

To show me how it’s done, Tsui jabs a thin spike into the fish’s brain with a quiet crunch-pop. Next he cuts the gill arches and vertically across the base of the fish’s tail to bleed it. Finally, he folds the tail back against the body, exposing the spinal cord and the neural tube that sits above it. He threads a long wire into the tube and reams it back and forth. The fish shudders and then lies still.

He looks up, still sliding the wire in and out like he’s plunging the fish. “Did you see the shiver?” he asks with a boyish grin before yanking the wire all the way out. With it comes a long white squiggle of rubbery tube. “That’s the spinal cord.”

He has me do the next one. The fish shudders under my hand as I slip the wire down the neural canal. “You’re literally stimulating the nerves,” Tsui explains.

“It’s absolutely clear that the more quote, unquote humane, the quicker you’re able to put that fish out of discomfort, the higher the quality is going to be.”

Tsui has a helpful tool for the job, a spike and a reamer that fit together and can be tossed in a tackle box. He’s negotiating a deal with a Japanese manufacturer to distribute them through the Ike Jime Federation, an advocacy, research, and consulting group dedicated to the practice. He and his team of five hope to encourage a market similar to the one for grass-fed beef and free-range chicken, for a premium product with a steeper price and a lessened moral burden. Over the past few months, they’ve been developing a series of educational web videos to release later in 2018.

“Fuck it, it’s been too fucking long that people have just been in the dark about the truth behind quality, and what the scientific consensus is,” Tsui says about why he’s releasing the videos for free, instead of charging for them. “There’s too much bullshit out there.”

As we talk, Tsui goes back and forth on the subject of fish pain. In his most unguarded moments, he calls suffocation “suffering to death.” But for him, as with many other advocates for fish welfare, any success demands a buy-in from an industry deeply invested in keeping fish pain a myth. “The data is clear that regardless of how you want to anthropomorphize the fish, those things suffer,” he told me on a recent phone call. “So I don’t care how you use these terms. It’s absolutely clear that the more quote, unquote humane, the quicker you’re able to put that fish out of discomfort, the higher the quality is going to be.”

Later, as I sat down to write this story, I pulled up the video of the fish struggling for air in the bucket. I felt nauseated, like I’d clicked on a PETA clip. I thought of the one and only fishing trip of my childhood, when a boatful of adults kept insisting bluefish couldn’t feel pain as one slammed itself repeatedly into the walls of a cooler.


It usually takes a lot longer for a fish to asphyxiate than it takes for a person to drown. As a trout convulses, it tears its own muscles apart; they flood with lactic acid and burn up their cellular fuel reserves, triggering a series of chemical reactions that speed the degradation of fat and muscle. The resultant meat is spongier than that from a trout that dies immediately, which makes it a grosser meal for us and a much more appealing one for bacteria. But even in the freezer, away from microbes, trout that suffocate go rancid a month sooner than those that get whacked in the head.

There’s plenty of scientific evidence that humanely killing fish slows rot and improves flavor, including in trout and horse mackerel. Humanely killing salmon improves fillet and skin color. Still, the vast majority of wild-caught fish asphyxiate. It’s cheaper, faster, and easier to let them asphyxiate in air, or on ice, or even to pump their water full of CO2, an ugly and painful way to die. In the US, there’s no regulatory body to protect fish the way the USDA (in theory) protects livestock from unnecessarily cruel deaths.

Other than ike jime, the generally accepted way to humanely kill a fish is electrical stunning, which renders them insensible before they’ve had a chance to panic. A tiny number of commercial fishing operations use this method, including one in the US that launched a custom-made commercial boat in 2016 with a built-in way to electrically stun large numbers of smaller fish, like crab and cod.

In Europe, farmed salmon are often killed using percussion to the brain, which is beginning to catch on slowly in the US. More commonly in America, farmed catfish are stunned with electricity and then beheaded and gutted before they have the chance to wake up.

Bluefin tuna is one of the only wild species that regularly gets slaughtered humanely. It’s a warm-blooded fish, so its meat degrades quickly during premortem stress, similarly to beef or pork. A single bluefin tuna can sell for tens or even hundreds of thousands of dollars at auction, so it’s worth it for workers to treat each fish with care.

“There’s a term on commercial boats: ‘Don’t burn the meat,’” Tsui tells me, describing the process of fishing for tuna. “Don’t let it exhaust itself on the line—bring that thing in. When the fish is struggling, it’s releasing lots of nasty flavors—adrenaline, lactic-acid buildup, and cortisol spikes in the blood.”

“Don’t let it exhaust itself on the line—bring that thing in. When the fish is struggling, it’s releasing lots of nasty flavors—adrenaline, lactic-acid buildup, and cortisol spikes in the blood.”

Tsui speaks from experience. After college, he got a job on a Hawaiian fishing boat. That’s where he first learned about ike jime. Since the Honolulu market serves both Japanese and American buyers, the fish they brought in went into two different buckets: fish bound for America went into a big cooler to asphyxiate, while fish headed for Japan went into a “live well,” a big tank along the side of the boat, to destress.

Because tuna are so huge—weighing up to 400 pounds for yellowfin, and nearly 1,000 pounds for bluefin—they can’t be brought on board alive; their thrashing could easily kill someone. When the fish is sufficiently relaxed, fishermen destroy the brain using a captive bolt gun or shotgun. If the tuna is bound for expensive sushi plates, the spinal cord is then reamed by hand with thick-gauge wire. This commercialization of ike jime on fishing boats has happened for one reason: profit. An unstressed tuna will be worth a fortune at auction. Burned tuna meat is easy for the trained eye to spot—it’s pale and mushy, unsuitable for high-end sushi.

That humane slaughter makes better food isn’t really a surprise. Farmers have known for a long time that if you let a cow, chicken, or pig freak out before you kill it, the meat will be degraded. In pigs and chickens, it’s called “pale, soft, exudative” meat, or PSE (exudate is fluid that leaks out of the meat). Higher body temperatures and the buildup of lactic acid in muscles create a chain reaction that screws up the color and texture, and also leads to meat that can’t hold water very well when it’s being cooled after butchering. In cows and sheep, the temperature and lactic acid in stressed animals turn into meat that’s “dark, firm, and dry,” or DFD.

PSE and DFD meat are real problems for the meat industry, leading to hundreds of millions of dollars a year in lost profits. The products have a shorter shelf life, and nobody’s going to buy them if they can see them. The meat can either be snuck into low-cost ground meat, or, if it’s totally beyond saving, dumped into dog and cat food.

But it took a bizarre lawsuit commonly referred to as “McLibel” to really change things. In 1991, McDonald’s sued two volunteers in a small activist group for printing a pamphlet accusing them of, among other things, animal cruelty. The seven-year court battle turned into a devastating self-own when the restaurant, having spent $16 million on lawyers, lost a significant portion of the case to two retirees who represented themselves.

This commercialization of ike jime on fishing boats has happened for one reason: profit. An unstressed tuna will be worth a fortune at auction. Burned tuna meat is easy for the trained eye to spot—it’s pale and mushy, unsuitable for high-end sushi.

Decidedly on the ropes, McDonald’s hired animal scientist Temple Grandin in 1997 to create welfare standards for their slaughterhouses. She focused on ways to keep the cows from being scared: nonslip floors, good lighting, making sure bolt guns were killing most animals on the first shot.

It’s hard to imagine a similar situation with wild-caught fish. There’s not one massive buyer who can set a blanket rule. Plus, the amount of money it would cost to humanely kill them all would raise the price to ten times what we currently pay, according to Culum Brown, associate professor of vertebrate evolution and director of Higher Degree Research at Macquarie University. “I can envision a future, maybe 10 or 20 years down the track, where wild fish are so rare maybe it will become a premium product, and people will be willing to pay for a fish that’s wild and killed humanely,” he told me. “My feeling is that most of the wild stocks will collapse long before we get to that position. It just won’t be economically viable.”

Which doesn’t mean he doesn’t have any hope. With so many wild populations in decline, aquaculture has taken over as the majority source of seafood in the world. Brown just thinks it will take government regulations, which will come only as a result of pressure from voters.

“We’ve given up on adults,” Brown told me. Aside from being a prominent researcher, he also speaks at schools and distributes educational materials in the hopes of pushing the world to care about fish welfare. “Kids have a natural empathy, and we kind of beat it out of them as they become adults. So I think that’s going to be the future—we’re basically targeting kids and aquaculture’s soft spots.”


The day before we killed the fish in his driveway, Tsui and I took a road trip to the Freshwater Institute, an aquaculture research facility in Shepherdstown, West Virginia, where animal and environmental scientists look for sustainable, market-friendly approaches to fish farming. Like Grandin, Freshwater’s scientists work to keep the fish calm, with appropriate densities of fish and a chill-out period before slaughter.

Driving with Tsui doesn’t instill that same calm. The biggest problem is that he talks with his hands—his whole body, really—especially on subjects he’s passionate about. And he is really, really passionate about changing the way Americans eat seafood.

“American chefs are asking for seafood, and the best shit is coming from overseas,” Tsui told me as we sped down a winding rural road in his pickup truck. He was steering with his knees so he could wave his hand around for emphasis while still being able to check his phone. “We’ve got fish out the wazoo here; we just don’t have sophisticated harvesting practices.” Grabbing the wheel for a moment, he took a turn so fast my pen skittered off the page of my notebook.

Most high-end sushi places in the United States—including Masa in New York and Uchi in Austin, Texas—fly in their fish daily or weekly from Japan. In fact, 93 percent of the seafood Americans eat is imported from other countries. (That number is a touch misleading, since some of that imported seafood is actually caught domestically, shipped out to places with cheap labor for processing, and then sent back to the US.)

Tsui’s argument is that if the fish caught locally were treated better, they’d taste better, which would encourage the generally fish-phobic American public to expand their palates beyond shrimp, salmon, tuna, and flavorless whitefish like cod (ten species make up 90 percent of all fish eaten by Americans). But for now, he and the other members of the Ike Jime Federation are carrying out their experiments on a fish they know Americans already like: Atlantic salmon.

The Freshwater Institute isn’t the ideal place to study how the flesh of a fish killed by ike jime compares to flesh acquired in a more typical way, because the institute was already killing all their fish using a top-of-the-line humane setup before the Ike Jime Federation came along. They’ve imported an industrial fish stunner from Australia, which simultaneously kills a fish with blunt-force trauma to the brain stem and cuts the gills to bleed them out. All that was left for Tsui to add was spinal cord destruction and enthusiasm.

Tsui’s argument is that if the fish caught locally were treated better, they’d taste better, which would encourage the generally fish-phobic American public to expand their palates beyond shrimp, salmon, tuna, and flavorless whitefish like cod.

Considering that the Freshwater Institute kills 20 metric tons (about 44,000 pounds) of fish a year, much of it sold as “Spring Hill Salmon” through D.C.-area Wegmans Food Markets, I was expecting something a little more industrial than the idyllic farm vibe I got as the truck’s tires crunched up the long driveway. The institute uses a recirculating aquaculture system, or RAS, a high-tech aboveground swimming pool that can be set up anywhere with a decent water supply. It avoids the ugliness and environmental hazards of open net pens and ponds, both of which are massive sources of water pollution and drivers of habitat destruction.

Walking out onto the floor of the RAS facility, I had to slosh both feet around in an inch of sanitizing solution. (Keeping out bugs is the best way to avoid having to use antibiotics.) Entering the enormous concrete room, I was hit with wet, earthy air, and the constant rushing and humming of an operation that continuously moves water, at a rate of 1,200 gallons per minute, through a maze of tubes, barrels, ladders, and tanks.

You can think of RAS as a high-tech version of a pet fish tank. Water from a giant aboveground pool circulates through a variety of filters, including physical barriers and vessels where bacteria break down waste products, all of which allows much of the water to be recycled.

Through a little submarine window in the side of the biggest tank, I could see salmon circling past, some darting and some ambling along against the circular current. Between the constant slushing of the water and the mesmerizing real-life screen saver, I was overcome by a deep sense of calm.

Then it was time to see where they’d die. In a room off to the side of the main floor, there’s a smaller tank, into which fish are pumped when it’s their time. After a week or so, they meet their fate: A worker in a poncho nets a rested salmon and slides it headfirst into an automated stunner. A pneumatic piston strikes the fish on the brain stem, killing it instantly, while a blade flashes up and cuts the gills and arteries. Then the fish is dropped into an ice slurry, to bleed out and cool off.

After rejecting outright asphyxiation for being cruel, and clubbing the fish by hand for being inefficient and easy to mess up, the institute landed on automated stunners, which they’ve been using ever since.

“In the old days, we tried carbon-dioxide gas. We soon found that fish would sense the high CO2 and try to tail-walk out of there,” Steve Summerfelt, director of aquaculture systems research at the Freshwater Institute, told me. The clear signs of distress fish demonstrate during CO2 poisoning have led to an outright ban on the practice in Norway and movement away from it in other European countries. The US, though, has no regulations at all on how you can kill a fish for food.

After rejecting outright asphyxiation for being cruel, and clubbing the fish by hand for being inefficient and easy to mess up, the institute landed on automated stunners, which they’ve been using ever since.

There’s plenty of evidence that killing fish with a blow to the head results in better food. But Tsui wanted to see if using the full ike jime process, including spinal cord destruction, made a significant difference. There were slight differences immediately after death, but a few days after slaughter, the color, texture, and pH levels were about the same, suggesting that a quick, calm death is the most important route to high-grade fish.


Fish farmers, of course, have a number of advantages over fishermen when it comes to humane slaughter. The fish killed at the Freshwater Institute are all nearly the same size and age, so you can set and forget the size parameters of the stunner. Everything is totally controlled, with no collateral damage to creatures like dolphins or sea turtles. So it’s much easier for them to commercially implement humane practices.

But what’s humane? Determining whether fish feel pain comes down to whether you can compare what fish feel to what we feel, given that their brains are set up differently than human brains. You can’t ask a fish using language; you just have to see what happens if you do something to a fish that would cause a person pain. Fish are hugely diverse, neurologically and anatomically. But generally, when shocked, poked, or injected with acid, they stop eating, try hard to get away, and avoid places where they’ve experienced so-called aversive stimuli in the past.

The scientific community has pretty much reached consensus at this point. In a 2016 issue of the journal Animal Sentience, biologist Brian Key wrote an article called “Why Fish Do Not Feel Pain.” More than 40 scientists wrote responses for the journal, and the vast majority disagreed with him.

Retired animal-welfare scientist Steve Kestin was unequivocal. “It really is a semantic argument. It doesn’t matter a damn which parts of the brain are doing the processing—the behavior of the animal indicates it’s just as much of a sensation as it is in humans.”

Kestin, who was a pioneer of fish-slaughter research during his time at the University of Bristol, in the United Kingdom, strongly believes humans need to treat fish better. But that’s a lot easier on a fish farm, where he believes quick brain destruction is the best option for most fish, than it is out in the ocean.

“On a commercial fishing boat, there’s no concept of animal welfare, or ending stuff in any humane way. They just get on with it,” he told me. “Until they’re chilled, quality will be lost … they come along the process line and are gutted alive. I’m sorry chaps, but that’s just how it is.”

The position of many scientists is that we just don't know if fish feel pain. But the industry should assume that they do, says Fred Conte, an extension aquaculture specialist with the University of California at Davis.

“Someone will put flowers on my grave before the question [of whether fish feel pain] is resolved,” he said. “But any company that assumes fish suffer and can come up with a method of humane slaughter is going to have the market advantage.”


Everyone assigns moral value to death on a spectrum; empathy comes factory installed but its targets don’t. For average Americans, the order is approximately: OK to kill for ethical reasons, such as to prevent suffering (dogs); don’t want to see the death and vaguely hope it’s not painful (cows); kill them on sight (cockroaches).

For most Americans, fish fall somewhere between cows and cockroaches. Pescatarians are included under the umbrella of vegetarianism, and fish flesh is usually billed as separate from meat. Fish are displayed in their full, corpsy glory on ice at the supermarket.

Whole Foods, which prides itself on ethical standards for the meat it sells, doesn’t display gutted, skin-on cow corpses. It displays a numerical rating system defining how well the animal lived and died. Each anonymous chunk of land-animal flesh has a little numbered sticker to tell you how good you can feel about the purchase.

Whole Foods bills its fish as “sustainably caught” rather than ethically treated, throwing their political weight behind environmental stewardship instead of lack of cruelty.

“I can’t taste your eco label; it doesn’t have a flavor. I’m all for sustainability, these things aren’t mutually exclusive, but it’s weird to me that for seafood, what’s important a lot of the time has nothing to do with taste,” Tsui told me when I asked him about sustainability versus a higher-quality seafood product. “I’m very confident that’s going to change. The consumer pressure is getting stronger.”

Whole Foods does proudly protect the welfare of one seafood item. In June 2006, Whole Foods stopped its sale of live lobster entirely, opting for frozen prekilled lobster instead. (Careful readers might note that every Whole Foods shopper’s favorite author, David Foster Wallace, published Consider the Lobster, a book of essays including his famous discussion of lobster-boiling ethics, in December 2005.)

“We place as much emphasis on the importance of humane treatment and quality of life for all animals as we do on the expectations for quality and flavor,” Whole Foods CEO John Mackey said in a press release at the time.

“At this point, our standards primarily are focused on sustainability of fisheries and farms,” Carrie Brownstein, global quality-standards coordinator for seafood at Whole Foods, told me when I asked what welfare standards Whole Foods uses for fish. Farmed catfish and farmed salmon sold at the stores are both killed using stunners; other welfare standards come as a by-product of sustainability mandates, like lower fish density and strict water-quality standards at fish farms.

“Honestly, the range of issues to tackle with seafood is really so big,” Brownstein said. “I feel like the animal-welfare component for fish is a really important one that I think is going to be something that we have to look at, but it hasn’t been the area we’ve focused on first.”

She’s got a point. An Associated Press investigation has uncovered rampant slavery within the seafood supply chain. It’s hard enough to find snapper untarnished by human-rights abuses, never mind worrying about whether the fish has been left to asphyxiate or gutted alive.


After killing the fish in his driveway in Virginia, Tsui set up a taste test in his kitchen. First he sliced up some of the trout that had been thrashing in the bucket. It was tough and flavorless.

“It’s all managed decomposition. That’s how natural flavors develop,” he told me.

Tsui then sliced up two striped bass fillets into sashimi, both from fish he’d killed the week before. “This fish right here was suffered to death—I’m sorry, suffocated to death,” he said, pointing with his knife. The other fish went through ike jime.

There was a marked difference between the two fillets. The ike jime fish was pale white at the edges, with a faint pink running up the center. The other was dusky rose because of hemorrhaging into muscle. Keeping in mind that this wasn’t a scientific test, and that I’d spent the past few days hearing all about how ike jime makes magic—I had to agree the ike jime fish was much better.

It had barely any of that fishy flavor I find off-putting, and the bite was smooth and firm, with a consistent texture throughout. The other fish was fine—as in, I would have happily eaten it in a strip-mall sushi joint—but in comparison it was hard to ignore the odd tang and the way it seemed to fall apart when I chewed. As someone who has contentedly eaten discount sushi, I’m probably not the target market for the upsell. But I could easily see foodies going nuts.

Yuji Haraguchi, proprietor of beloved Brooklyn sushi spot Okonomi, also wants to change American minds about local seafood. But he thinks that people will first have to eat fish at home before they’ll care about how it’s killed. That’s why he started Osakana, a small, local-seafood-only fish store in Brooklyn that holds classes on how to prepare and cook different local seafood. The store’s tagline is “Honor your fish.”

“Right now people don’t cook fish at home at all. It’s very rare that people think of fish as an option for every day,” he told me over the phone.

Haraguchi wants to bring a different aspect of Japanese culture to American seafood: knowing how to buy a fish and what the hell to do with it to make it taste good.

“Ike jime is a good process, but I think that’s way too much information,” he said. “We want to break that barrier in the most friendly way—I don’t want to do the ike jime demonstration in front of customers and freak them out.”

I asked him if he has any ethical concerns about how fish are killed. “I agree with you that how people handle fish here is not respectful,” he told me. For instance, he once saw a fisherman literally standing on a living fish on the deck of a boat.

“There’s no respect from the consumer. If the one piece of fish he was standing on was $100,000, he wouldn’t be standing on it,” Haraguchi pointed out. “It’s a living thing, but money is the more typical reason.”

Tsui thinks there’s no reason to separate the two when trying to market the fishy version of Kobe beef. “In my mind, it’s just as important to have the conversation about animal welfare as it is to have a conversation about the final product. You can’t have one without the other.”

Share this story

Loading more