Shortly before 7:45 a.m., the slaughterhouse workers trudged inside the nondescript building at the end of a dirt road and headed to what they called the "kill floor." There, when no one was looking, one of them would flip on a hidden camera and record the animals writhing on a conveyor belt.
The worker was an undercover investigator for an animal rights group, Animal Equality, which had conducted hundreds of such investigations around the world.
But this one was among the more unusual. It involved not pigs or cows or chickens, but fish.
Over five weeks beginning in August 2020, the investigator at the facility, a catfish farm in central Mississippi, documented fish dumped onto a conveyor belt and left to suffocate when workers took breaks, according to Animal Equality. The investigator also shot video of turtles and unwanted fish abandoned in buckets without water for long stretches of time before being chopped up alive in an industrial machine, according to the group.
The investigation is a new front in the effort to improve the treatment of animals that end up on American dinner plates.
"If one pig were killed in this manner, the slaughterhouse would be shut down," said Sean Thomas, international director of investigations for Animal Equality.
More than 50 years ago, the U.S. installed legal guardrails to reduce the suffering of commercially slaughtered animals like pigs and cows and goats.
Fish have traditionally been seen in a different light. But a growing body of research rebuts the long-held view that fish, unlike mammals, do not feel or sense. The science, many experts say, indicates that fish do, in fact, feel pain.
The conclusion could have major implications for fisheries in the U.S. It also raises polarizing questions: Should people be criminally charged for abusing fish, and if so, what should the legal standard be?
Animal cruelty laws differ by state. Some are explicit about the animals covered under criminal statutes. Others are less so, leaving them open to interpretation.
The laws in Mississippi do not exclude fish, legal experts said. But getting a prosecutor to crack down on a place for alleged fish abuse is another matter.
Animal Equality laid out its findings in an email to the prosecutor in Yazoo County and called for a criminal investigation into the catfish farm.
After a long silence, Yazoo County prosecutor John Donaldson finally wrote back.
"I'm not interested in any of this," he wrote, according to an email shared with NBC News.
Michigan State University law professor David Favre, an expert on animal cruelty laws, said he was not surprised that an animal rights group had struggled to persuade a prosecutor to pursue a criminal case against a catfish farm.
"Would a prosecutor really go and present a case to a jury about fish?" Favre asked. "I don't think that's very likely.
"But if they wanted to try it," Favre added after reviewing the Mississippi laws, "they'd definitely have the legal basis."
The science of fish pain
Lynne Sneddon, a biologist at the University of Gothenburg in Sweden, has been studying whether fish feel pain for more than two decades. Her research began with some basic questions.
Do fish have the nervous systems to detect pain?
"The answer is yes," she said in an interview. "Is that information conveyed to the brain? It is, indeed."
Her research has shown that fish, when under duress, stop engaging in such basic behaviors as eating. In one study, she found that fish subjected to injections of acetic acid returned to normal swimming and eating patterns after receiving painkillers. In another, fish given a painful stimulus to their lips were observed rubbing their mouths against the side of a tank, much as a human might rub a toe after stubbing it.
"There's lots and lots of evidence that fish are sentient beings," Sneddon said. "Really, there's no reason we should be treating them any differently from mammals."
Not all scientists are convinced. A 2013 study concluded that while fish might respond to painful stimuli, they lack the neurological capacity to experience conscious feelings of pain.
But the idea that fish are sensory beings that experience suffering has been gaining momentum in areas outside of scientific journals.
In 2013, the American Veterinary Medical Association published new guidelines for euthanizing animals, which referred to the research finding that fish feel pain.
"The preponderance of accumulated evidence supports the position that finfish should be accorded the same considerations as terrestrial vertebrates in regard to relief from pain," the guidelines read.
Fish are not protected under the federal Humane Methods of Slaughter Act, a 1958 law requiring that pigs, cows and other commercially slaughtered mammals be spared needless suffering. Catfish farms are inspected by the Agriculture Department, but the inspections focus only on whether the animals are prepared and processed in sanitary conditions.
It is very rare, indeed, but prosecutors have brought criminal charges for allegations of fish abuse.
In March 2020, an Ohio fishery was charged by the state Department of Natural Resources Wildlife Division with illegally removing and abusing fish, a native species called gar and a trophy-size muskellunge, from Lake Erie.
The Szuch Fishery pleaded not guilty to one count of causing intentional injury to a noncommercial fish species, among other charges. The case continues, and the fishery did not respond to a request for comment.
In an even more unusual case, a North Carolina man was arrested on animal cruelty charges in 2019 after he was alleged to have left behind his fish when he was evicted. The Oscar fish had developed a parasitic disease caused by malnutrition and poor water quality.
But the charges were dropped after prosecutors determined that the state statute on animal cruelty does not include fish. It defines animals as "every living vertebrate in the classes Amphibia, Reptilia, Aves and Mammalia except human beings."
In Mississippi, two of the statutes that regulate harmful behavior toward animals include no language that excludes fish. They instead refer to "any living creature" except dogs or cats, which are covered under separate statutes.
Kathy Hessler, director of the Animal Law Clinic at Lewis and Clark College in Portland, Ore., analyzed Mississippi's animal cruelty laws in a memo for Animal Equality.
"The language within the chapter is not ambiguous or unclear and therefore must be read as written to apply to fish and turtles," she wrote.
The Yazoo County prosecutor took a very different view.
"There is no authority in Mississippi for what you are proposing to do under those two statues," Donaldson wrote in an email to an Animal Equality representative. "In addition my wife and I both hunt and fish and eat what we kill as do a majority of the people in this state. I have much more to do as a prosecutor than to waste my time with this."
When asked for comment, Donaldson said in an email that "there was nothing" to the allegations.
"I am completely familiar with the operation as both my son and daughter in law worked in the plant," he said.
The fish farm targeted in the investigation, Simmons Farm Raised Catfish, does take steps to ensure that its animals are killed humanely, company representatives say and Animal Equality confirmed. The farm uses a water-filled truck to transport the catfish to the processing plant and passes them through an electrical stunning device before they are beheaded.
But not all of the fish are knocked out before their heads are chopped off, according to the undercover video provided by Animal Equality. Fish are also sometimes left on the conveyor system for more than 30 minutes — out of water — when workers go on breaks, the group alleges.
Bill James, a consultant for the Catfish Farmers of America, an industry group, who also speaks on behalf of Simmons, dismissed the investigation as silly and misguided.
James said that of the billions of fish killed for food every year, catfish farmed in the U.S. are probably the best-treated species on the planet.
"The farmers that raise the catfish have a vested interest in making sure the fish are treated humanely," said James, who retired as the chief public health veterinarian at the Agriculture Department's Food Safety and Inspection Service. "That water is properly oxygenated, that diseases are controlled, that fish are appropriately fed. Those fish have it easy compared to wild fish."
James said farms like Simmons' keep the catfish in water right up until they are incapacitated by stunning devices.
"I've seen the videos that were taken," James said. "Compared to videos showing inhumane treatment of animals that have surfaced in the past, this is nothing."
The farm is also in good standing with the Agriculture Department, according to James and publicly available records.
"Why they have chosen to focus on a catfish establishment that conducts the best practices in the world is beyond me," James said. "It is from my perspective like a petulant vendetta."
James also said catfish imported into the U.S. far outnumber those raised domestically. "If they really cared about fish," James said of the animal rights group, "they would go after fish in a bigger pond."
Thomas, Animal Equality's director of investigations, said James' argument was a "philosophical ruse — there might be something worse, so whatever we do isn't bad."
"That's not our point to say there isn't any other abuse going on that we would like to highlight," he said.
Thomas said the group chose to target catfish farms because they are unique in the U.S. for having formal slaughterhouse facilities that are already inspected by a federal agency.
"We're not saying catfish are the most abused fish of all the species consumed in the U.S., but they have this unique place already within USDA's scope of consideration," he said. "This is our first step forward."
Animal Equality's broader goal is to push lawmakers to amend the Humane Methods of Slaughter Act to expressly include catfish slaughtered at Agriculture Department-inspected facilities.
Favre, the Michigan State University law professor, said he expects that more attention will be paid to how fish are treated at places like commercial fish farms.
"It hasn't been a social issue before, but it's now percolating in society," Favre said.
"Should we really be thinking about fish, too?" he asked. "We don't really know how people are going to come out on that."
But, he added, "we didn't use to care about chickens."