Troubled Waters: The Case Against Eating Fish

Richard H. Schwartz

There are standard questions that vegetarians are often asked. Perhaps the most frequent one is, “How do you get enough protein?” Another common question is, “Do you eat fish?”

Many people, including some who call themselves vegetarians, think fish are less capable of suffering than mammals and birds. These would-be vegetarians may avoid eating mammals and birds while continuing to eat fish, sometimes arguing that the problems associated with the production and consumption of other animal products don’t apply to fish. After all, they reason: fish aren’t raised in the cruel confinement of factory farms; unlike the raising of “livestock,” fishing doesn’t cause soil erosion and depletion, require deforestation to create pastureland and land on which to grow feed crops, or require huge amounts of pesticides and irrigation water; also, fish flesh is generally lower in fat than other animal-derived foods and is a healthy food. All of these assumptions are either wrong or problematic.

Let us consider typical vegetarian arguments that address treatment of animals, health risks, and environmental sustainability, as they apply to fish "production" and consumption. Even though by definition fish (and other aquatic animals) have never been considered part of a vegetarian diet, the reasons to avoid their consumption as you will see are compelling.


Fishers and animal rights advocates have long debated whether or not fish can feel pain. Among the overwhelming evidence that fish can suffer is a recent report by a team of marine biologists at Edinburgh’s Roslin Institute. The report was published by the Royal Society, one of Britain’s leading scientific institutes. The researchers found that rainbow trout possess pain receptors and react to a harmful substance (in this case, acetic acid) with “profound behavioral and physiological changes . . . over a prolonged period, comparable to those observed in higher mammals.” The researchers concluded that their findings “fulfill the criteria for animal pain.” Their conclusion is also consistent with common sense: fish, like other animals, need to be able to feel pain in order to survive.

Methods of catching and killing fish are clearly abusive. When fish are hauled up from a considerable depth, the sudden change in pressure on their bodies causes painful decompression that often causes their gills to collapse and their eyes to pop out. As soon as fish are removed from water, they begin to suffocate.

Hooked fish struggle because of pain and fear. As described by Tom Hopkins, professor of marine science at the University of Alabama, getting hooked on a line is “like dentistry without Novocain, drilling into exposed nerves.”

Fish who are “farmed” rather than caught experience more-prolonged suffering. Today in the United States, (to maximize profit,) most “farmed” trout, salmon, catfish, and other fish are raised in the same sort of intensive crowding found in commercial chicken and pig operations. Like the chicken-flesh industry, fish “farming” involves large-scale, highly mechanized production. Thousands of fish are crammed into ponds, troughs, or sea-floating cages, so that fish farmers can raise the greatest possible number of fish per cubic foot of water. In most cases, each fish is allotted a space scarcely larger than their body.
Farmed fish are fed pellets designed for unnaturally rapid weight gain. Under these abnormal intensely crowded conditions, fish suffer from stress, infections, parasites, oxygen depletion, and gas bubble disease (similar to “the bends” in humans). In an effort to prevent the spread of disease among the fish, producers give them large amounts of antibiotics. Even so, many fish die before slaughter. For economic reasons and to reduce fish feces, most farmed fish are starved for days or weeks before they're slaughtered.

Fish are not the only animals to suffer because of people’s appetite for their flesh. Egrets, hawks, and other birds who eat fish commonly are shot or poisoned to prevent them from eating the captives of these large open pools. Also, many sea turtles, dolphins, sea birds, and invertebrates suffer horrible deaths in commercial fishing nets.


Many people who eat fish erroneously believe that it’s a healthy food. In a 1997 survey commissioned by the National Fisheries Institute, more than half of the 10,000 surveyed households cited health benefits among their primary reasons for eating fish.

What are the actual health effects of consuming fish? Fish flesh contains omega-3 fatty acids which appear to be heart-protective. However, there are healthier plant-based sources of these acids, especially flax seeds, and, in lesser amounts, canola, soybean, walnuts, tofu, pumpkin, and wheat germ. Further, these plant foods provide health-promoting fiber and antioxidants. And they don’t contain the toxic heavy metals and carcinogens found in fish flesh.
n any case, the possible benefits of omega-3 fatty acids are largely limited to people at risk of heart disease, and for pregnant and breastfeeding women. The largest study of cholesterol levels, carried out in Framingham, Massachusetts, showed that people with cholesterol levels below 150 have virtually no such risk. Because people on well-planned vegan diets generally have cholesterol levels below 150, the best way to maintain cardiac health is to follow such a diet, thereby ensuring that artery blockages don’t occur in the first place.

As a result of human pollution of aquatic environments, eating fish flesh has become a major health hazard. Industrial and municipal wastes and the agricultural chemicals flushed into the world’s waters are absorbed by the fish who live there. Big fish such as tuna and salmon eat smaller fish so, in general, the bigger the fish, the greater the accumulation of toxic chemicals throughout their flesh. Pollutants that concentrate in fish include pesticides; polychlorinated biphenyls (PCBs); toxic metals such as lead, cadmium, chromium, and arsenic; dioxins; and radioactive substances such as strontium 90. Because of biological magnification during movement up the food chain, pollutants can reach levels as high as 9 million times that of the water in which they live. These pollutants have been linked to many health problems, including impaired behavioral development in children. Nursing infants consume half of their mother’s load of PCBs, dioxin, DDT, and other toxic chemicals. These toxins have been linked to cancers, nervous system disorders, fetal damage, and many other damaging health effects.  Dr. Neal Barnard, director of Physicians Committee for Responsible Medicine (PCRM), describes fish as “a mixture of fat and protein, seasoned with toxic chemicals.”

Higher mercury levels in mothers who eat significant amounts of fish have been associated with birth defects, mental retardation, seizures, cerebral palsy, and developmental disabilities in their children. A U.S. Environmental Protection Agency (EPA) analysis released in 2004 indicated that about 630,000 of the 4 million children born annually in the U.S. are at risk of impaired motor function, learning capacity, memory, and vision - due to high levels of mercury in their bloodstreams.

The Food and Drug Administration and the EPA have advised that groups most sensitive to mercury — women of childbearing age and young children — should not eat swordfish, king mackerel, or shark because they’re high in mercury. Removing fish from the diet eliminates half of all mercury exposure and reduces one’s intake of other toxins.

“Farmed” salmon contains even more contaminants than flesh from wild-caught salmon. As Reported in Science, an analysis of over 2 tons of flesh from salmon “farmed” in different countries indicated toxic levels of PCBs, dioxins, and banned insecticides such as toxaphene. The risks are so great that the EPA’s guidelines, suggest that no one should eat flesh from “farmed” salmon more than once a month. The authors of the Science report warn that girls and young women should eat even less because pregnant women can pass on fish-flesh contaminants to their fetuses, impairing mental development and immune-system function. Two studies published in the journal Chemosphere in 2003 also reported elevated levels of PCBs, and certain chemicals, including flame retardant, in flesh from “farmed” salmon. Most salmon in U.S. markets today are farmed.

It’s easy to understand how industrial toxins accumulate in the flesh of ocean-dwelling fish, but how did farmed salmon get so contaminated? Most farmed salmon are fed pellets made from fish hauled up from the polluted sea floor. It takes 3 to 4 pounds of wild fish to produce just one pound of “farmed” fish.

“Farmed” fish also are fed dyes to give their flesh a pink color, as well as massive amounts of antibiotics to stave off bacterial diseases and sea lice. Farmed salmon are fed more antibiotics, per pound, than any other animals reared for slaughter. This contributes to increasing numbers of drug-resistant bacteria, making it more difficult to treat some human diseases.

In a six-month investigation, Consumers Union found that nearly half the fish tested from markets in New York City, Chicago, and Santa Cruz, California were contaminated by bacteria from human or nonhuman feces. In addition, fish often contain disease-causing worms and parasites.

Even when carefully handled and continually refrigerated, dead fish rapidly rots. Fish often stay on trawlers for long periods before being brought to markets.

Fish flesh contains large amounts of protein. While most people think this is positive, the average American consumes excess protein, which has been linked to a number of health problems, including kidney stones and osteoporosis. Unlike fats and carbohydrates, protein can’t be stored by the human body. Any consumed protein that exceeds the amount that can be used on a given day is broken down and excreted. After someone eats concentrated protein, such as a salmon steak or fish fillet, their blood must be cleansed of protein wastes, such as urea, ammonia, and amino acid fragments. Since cleansing requires calcium, the excess protein from fish causes the loss of calcium through the urine. Continued year after year, this calcium loss may result in thin bones that easily fracture: osteoporosis, a condition that affects 15 million Americans. Due to lower acid production, vegetable protein generally causes much less calcium loss.

Fish contain none of the protective phytochemicals found only in plant-derived foods. Also, fish flesh has no fiber and virtually no complex carbohydrates. Lack of fiber may contribute to a number of diseases related to digestion, such as diverticulosis and colon cancer.

While fish is generally lower in fat than other animal-derived foods, not all fish is low in fat. Fifty-two percent of the calories in salmon flesh are from fat. In the case of many fish, such as catfish, swordfish, and sea trout, almost one-third of the calories are from fat. While fish fat is generally unsaturated and therefore doesn’t increase cholesterol in the blood of consumers, it does contribute to the build-up of toxins. Studies show that diets heavy in fish do not reverse arterial blockages. In fact, blockages often continue to worsen in patients who regularly eat fish.


Another very serious, and escalating, problem is the impact that fishing and fish “farming” have on the environment. Modern commercial trawlers are the size of a football field, with huge nets (sometimes miles long) that scoop up everything in their path. They can take in 800,000 pounds of fish in just one netting. Trawlers scrape up ocean bottoms, destroying coral reefs. Half of the fish and other sea creatures (including some protected species) obtained through commercial fishing are fed to animals reared for food, including “farmed” fish. Each year, about 30 million tons of aquatic animals, maimed, dying, or already dead, are simply tossed back into the ocean.

Commercial fishing fleets are rapidly destroying aquatic ecosystems. As a result, the number of large predatory fish has dramatically declined over the last 50 years. Once-huge populations of tuna, swordfish, and cod have dwindled to mere remnants. Dalhousie University biologist Ransom Myers has stated, “Unless we seriously control industrial fishing worldwide, many of the species will go extinct.” The ocean’s biodiversity rivals that of tropical rainforests. In effect, humans are clear-cutting these environments. Waters that once teemed with life are now so barren that they’ve been compared to a dust bowl.

Plummeting fish populations have ripple effects throughout the marine ecosystem. Predator–prey relationships have been disrupted. For example, a decline in pollack in western Alaska has caused a 90 percent decline in Steller's sea lions, who are now listed as endangered. Because of the decrease in sea lions, who are orcas’ primary prey, orcas have been eating more sea otters. As a result, sea otters have declined by 90 percent since 1990.

As vessels scour increasingly fished-out waters, international confrontations are increasing. Russians have attacked Japanese vessels in the Northwest Pacific. Scottish fishers have attacked a Russian trawler. Norwegian patrols cut the nets of three Icelandic ships in the Arctic, and the crews exchanged shots. The United Nations has reported a sharp increase in piracy and armed robbery directed toward ships, many of them fishing vessels.

“Aquaculture,” too, has a significant negative impact on the environment. First, native fish are displaced as introduced fish invade spawning grounds and compete for food. Interbreeding pollutes the genetic pool. According to the National Fisheries Research Center, “aquaculture” has contributed to 68 percent of fish extinctions worldwide.

Fish “farming” also depletes natural resources. Modern commercial fishing is extremely energy-intensive. It requires as much as twenty calories of fossil-fuel energy to produce one calorie of energy from fish. Moreover, where fish are grown in artificial ponds, vast amounts of water are required to replenish oxygen and remove wastes. Rearing a ton of fish for slaughter requires eight tons of water. Producing one pound of flesh from captive fish requires three to four pounds of flesh from wild fish, so people who eat farmed fish contribute to the decimation of free-living fish populations.

“Aquaculture” also results in enormous pollution. The intense accumulation of wastes from fish farms can pollute the local marine environment and spread illnesses. Researchers at the University of Stockholm have found that pollution from fish farms can extend to an area much larger than the farm itself. In Scotland, for example, caged salmon contaminate coastal waters with untreated waste equivalent to that produced by 8 million people.
Because it requires massive water use, “aquaculture” routinely is conducted on coastal land that is the prime breeding and spawning ground for many free-living fish. Much coastal land has been cleared of forests, swamps, and rice patties to make room for fish “farms.”

Antibiotics given to farmed fish harm nearby seas and oceans. When farmed fish, laden with antibiotics, escape and breed with free-living fish, aquatic ecosystems may be thrown out of balance because of the mating of wild and farmed fish. Escaped fish raised in intensive confinement may spread disease to free populations of fish.

The “production” and consumption of fish flesh causes great suffering to fish and other animals, harms human health, threatens aquatic biodiversity, wastes natural resources, and invites international conflicts. A shift away from eating fish is both a societal and moral imperative.


Richard H. Schwartz, Ph. D, is the author of Judaism and Vegetarianism, Judaism and Global Survival, and Mathematics and Global Survival. He has over 100 articles on the Internet at, and frequently speaks and contributes articles on environmental, health, and other current issues. He is
Professor Emeritus of Mathematics at the College of Staten Island, President of the Jewish Vegetarians of North America (JVNA), and Coordinator of the Society of Ethical and Religious Vegetarians (SERV). e-mail address:

Many thanks to Joan Dunayer, Jay Lavine, M.D., Michael Greger, M.D., and Dawn Carr for their valuable suggestions re this article.


Richard H. Schwartz, Ph.D.
Professor Emeritus, College of Staten Island
Author of "Judaism and Vegetarianism," "Judaism and Global Survival," and "Mathematics and Global Survival," and over 130 articles at
President of Jewish Vegetarians of North America (JVNA)
and Society of Ethical and Religious Vegetarians (SERV)
Associate Producer of A SACRED DUTY (
Director of Veg Climate Alliance (