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menu Big Fish: The Aquacultural Revolution
San Pya wholesale fish market in Yangon, Myanmar
At the San Pya wholesale fish market in Yangon, Myanmar, the trade in farmed fish has grown enormously over the past few decades. Photo by Sai Aung Main/AFP via Getty Images

Hold the Salt: The Promise of Little Fresh Fishes

In Southeast Asia, aquaculture production from medium-sized freshwater farms is growing quickly. Meet the quiet revolution that could sustainably feed the world.

Authored by

by Paul Tullis
with reporting in Myanmar by Htoo Tay Zar

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Tens of thousands of kilograms of white carp, rohu, stinging catfish, eel, red snapper, grouper, snakehead, gagata, bream—the list goes on—surround fish broker Ko Thar Gyi at the San Pya wholesale fish market in Myanmar’s colonial capital, Yangon. The scent is overpowering. He’s been here since 4 a.m., which is when he and his fellow brokers arrive each day to meet the fishers in their lantern-lit, smile-shaped wooden boats. The fishers—arriving from the Yangon River—nose their boats up to shore, engines gurgling and heavy with fish. Each vessel carries up to 10,000 kilograms of product, says Thar (Ko and Gyi are honorifics in the Burmese language).

San Pya is the largest fish market in Myanmar’s largest city and commercial center, and the key point in the supply chain of fish for human consumption in the region, also called Yangon. Dozens of seafood processors and exporters operate in and around the market and its smaller cousin, Shwe Padauk, a few kilometers up the river. San Pya has become so busy, Thar says, that he has opened a second branch of his operation at Shwe Padauk.

San Pya and Thar’s business are thriving despite the decline of wild fisheries in much of Asia and indeed the world—globally, only two-thirds of fish stocks are within biologically sustainable levels, down from 90 percent in 1974, according to the Food and Agriculture Organization of the United Nations (FAO). San Pya’s bustle continues unabated because while the ocean’s bounty has faltered, a growing share of the product is supplied by fish farms—from almost nothing when the market opened in 1991 to 60 to 75 percent in 2014, when researchers from Michigan State University and Myanmar’s Centre for Economic and Social Development polled sellers. This mirrors a global trend: fish consumption has more than doubled per capita since 1961, with nearly the entire increase coming from aquaculture in the past three decades. People are eating much more fish, but the difference isn’t coming from wild catches.

Aquaculture now accounts for more than half of the fish we eat, worldwide, increasing from only four percent in 1950. It’s become so lucrative in Myanmar, Thar says, that companies from China “are buying paddy fields for more than market price and turning them into fish farms.”

boats at San Pya wholesale fish market

Boats deliver hundreds of thousands of kilograms of fish to the San Pya wholesale fish market in Myanmar via the Yangon River, arriving by 4 a.m. Photo by Htoo Tay Zar

An astute business person, Thar also operates a fish farm in the township of Pantanaw, around 95 kilometers northeast of the market, where he raises mainly rohu, white carp, and prawns in freshwater ponds. But the San Pya business is his main focus, he says, and with good reason: he grosses around US $5,800 each workday, buying fish and selling it to processors, exporters, and local residents. It’s an enormous figure in a country where per capita income is about a quarter of that per year. He says most of his product comes from the regions of Myanmar that collectively form the seat of the country’s aquaculture production. The acreage of cultivated fishponds there expanded between 2003 and 2014, in some regions by more than 250 percent. The vast majority of the fish is consumed domestically, and three of the five big brokers inside San Pya specialize in farmed fish. “Business is good these days,” Thar says.

Though Thar doesn’t seem to mind, aquaculture has a bad reputation in some circles. The narrative in North America and Europe among environmentalists and those concerned with global development is that it damages ecosystems and saps poor countries of their natural resources, with much of the product exported, leaving little of the wealth or nutrition it generates in the communities that actually grew and tended the fish. And for certain species, in certain places, that’s true: salmon farming in Chile and North America’s Pacific Northwest has been linked to outbreaks of parasitic diseases and the introduction of non-native species into wild populations. In Vietnam and other places, shrimp farming—often for export to wealthy countries in North America and Europe—incentivized destruction of mangroves, which are among the most carbon-rich forests in the tropics, sequestering more planet-warming carbon dioxide per hectare than the Amazon rainforest. Reading media accounts—many of them based on academic literature that until recently often focused on shrimp and salmon, and the negative impacts of aquaculture exports on poor countries—few people can be faulted for concluding that aquaculture is deeply problematic for the environment, sustainable development, and equity. But the story is far more complex.


The binary viewpoint—aquaculture is bad, sustainable wild capture is good—frustrates Ben Belton, a developmental economist in Michigan State University’s Department of Agricultural, Food, and Resource Economics. His research indicates that as the Earth’s population closes in on 10 billion, aquaculture—particularly medium-scale freshwater operations such as those abundant in the area Thar buys from—could be an important and sustainable supplier of food. Over 15 years of researching aquaculture in Southeast Asia, Belton has witnessed what researchers, including himself, call a quiet revolution, a fundamental change overlooked by much of the Global North: aquaculture in Southeast Asia is growing fast and driven mainly by medium-sized enterprises on a few inland hectares.

Many of the biggest fish brokers at the San Pya market trade in farmed fish. Video by Maung Nyan

“There’s this bias that’s been shaped by what people in the Global North perceive to be important, because what do they see? They go to the supermarket and they see [farmed] shrimp and salmon,” says Belton.

In North America’s biggest market, the United States, two of the top three consumed “fish”—defined by the FAO as finfish, crustaceans, mollusks, and other aquaculture animals—are shrimp and salmon. But these species are a tiny portion of the volume of fish produced by aquaculture. In 2018, 90 percent of fish farmed globally were species other than shrimp and salmon, according to the FAO. Shrimp accounts for virtually none of the aquaculture in Myanmar, and only about four or five percent in neighboring Bangladesh, the world’s fifth-largest aquaculture producer. (Salmon can’t survive at their latitude.) In Myanmar, and in the five countries with the highest aquaculture production, pond-based freshwater aquaculture dominates—and pond aquaculture tends to have a much lower environmental impact than marine fish farming.

Other researchers, such as Simon Bush, a professor and chair of the Environmental Policy Group at Wageningen University and Research in the Netherlands and a member of the technical advisory board of the Monterey Bay Aquarium Seafood Watch program, share Belton’s critique of the predominant narrative. “You can’t just take that image of those two species and then say that all aquaculture has this environmental impact,” Bush says. And a 224-page report the FAO put out this year, The State of World Fisheries and Aquaculture: Sustainability in Action, backs them up, calling fish “some of the less impactful [foods] on the natural environment.”

Although malnutrition has been on the rise since 2015 after decades of retreat, paradoxically, incomes worldwide have grown during the same time. An expanding, wealthier population will mean unprecedented demand for protein because as people’s spending power grows, they seek more protein in their diets. Alongside growing fish consumption, in the past two decades meat production has risen by 35 percent, milk by 32 percent, and soy by 73 percent—all outpacing population growth.

This is not sustainable. Cattle produce problematic amounts of greenhouse gas emissions. Carbon-sequestering rainforests are cleared to provide them with pasture. Soy—much of it grown to feed those cattle—also contributes to the depletion of carbon dioxide stores (at a rate second only to the cattle themselves, according to the World Wildlife Fund).

So, to feed a growing, wealthier population without ruining the ability of its only home to produce food, there will need to be a role for fish. Proper management of fisheries can maintain ecosystem health—and even rebuild it—but fisheries are not always properly managed. That leaves aquaculture. When the alternative to protein from fish is land-based meat, Bush says, “per unit of production, aquaculture comes out at the better end of the spectrum, environmentally speaking. Especially the freshwater systems.”

pile of fish at San Pya wholesale fish market

The wholesale fish market distributes the fish raised in converted rice paddies in areas far from Myanmar’s commercial center, Yangon. Photo by Htoo Tay Zar

Intensification of freshwater aquaculture is growing. But as practiced in Myanmar and its neighbors India, China, Bangladesh, Laos, and Thailand, it is less reliant on manufactured feed and has nowhere near the same level of environmental impacts as shrimp and salmon. With technology and mechanization making it more efficient, the plentiful harvest has driven down the price of fish, making the protein- and micronutrient-rich food available to more consumers. People in low-income, food-deficit countries such as those in Southeast Asia are the ones who need such food the most, and aquaculture is more likely to provide affordable protein than other foods. The fishponds of smallholders are not supplying the luxury fish sold in upscale North American and European markets; they’re feeding their neighbors. One survey of 10 countries in Africa, Asia, and South America showed that were it not for aquaculture, the poor would eat far less fish of any kind, wild or farmed. And Belton and his colleagues estimate 70 to 80 percent of farmed fish moving through San Pya is for the domestic market, and not for export. Across the border in Bangladesh, 94 percent of the total market in aquaculture is consumed domestically. “It’s very clear the vast majority [of Southeast Asian aquaculture] is being consumed in the same places it’s being produced,” Belton says.

Southeast Asia has no monopoly on the potential of aquaculture to feed a growing population of humans while conserving the planet. The practice is expanding in West Africa, one of the areas of the globe where populations are expanding fastest. And Belton’s work shows that a lot of the methods used in Myanmar and Bangladesh can readily be exported to Nigeria, Gabon, or virtually anywhere else with a reliable supply of fresh water.


Workers shout to clear the path ahead of them as they lug red, orange, and blue laundry baskets full of fish packed in ice from the 10 docks outside San Pya to Thar’s operation and others. They strain to be heard over the engine noise of the boats behind them and the rain hitting the tin roof above. Once emptied of their cargo, the boats return upriver to gather another load from aquaculture farms. Some of their haul could well come from the farm of Ko Kyaw Sein Tun, who operates ponds in northwest Pantanaw township, where Thar sources some of his farmed product.

Workers unload fish as loaded boats arrive at the wholesale fish market

Workers unload fish as loaded boats arrive at the wholesale fish market. Photo by Htoo Tay Zar

Growing up, none of Kyaw’s family worked in farming or fish farming, but, seeing an opportunity when he finished school 20 years ago, he went into business for himself with a single small pond. Today, he owns or operates 10 ponds—the largest one covers the same area as 16 Olympic-sized pools—filled with rohu, prawns, and white carp. A dozen or so men stand waist-deep in a nearby pond, pulling a net full of Kyaw’s shimmering, silvery product to shore, where the laundry baskets wait, ready to be filled and taken to the scales.

A typical way to start an inland aquaculture business in Southeast Asia is to convert a rice paddy. The government tightly controls the use of agricultural land in Myanmar, but that hasn’t stopped many enterprising individuals from risking fines and switching to freshwater aquaculture instead, either converting their own paddies or leasing land from others. Land already in use for rice is actually best suited for freshwater ponds, so growth of aquaculture in rice-producing regions—which stretch from Asia to Egypt to West Africa to California—involves little destruction of relatively pristine habitat for the small- and medium-sized farms, Belton found in his research.

When Kyaw was starting out, a legion of workers with strong backs constructed most ponds, and even today teams of diggers travel from village to village offering their services. The most common route from paddy to pond, though, is to hire a backhoe. A trench is dug around the rice field, with the excavated soil used to build up dikes beside it—it’s not so much digging a hole as removing soil and banking it on the sides. Lime is added before water, which sometimes means waiting for rain. Depending on the pond’s location relative to a water source and how much it would cost to rent and fuel the machine, however, farmers might pump in some groundwater and let the rain fill the rest. The lime, a calcium-rich mineral, disinfects the pond bed and changes the pH of the water to make it more suitable for the growth of phytoplankton, one food source for farmed fish. The practice is essentially the same as a farmer fertilizing grass to create a pasture for cattle.

At Ko Kyaw Sein Tun’s fish farm about 70 kilometers from Yangon, the aquaculture economy is bustling, providing many locals with employment. Video by Maung Nyan

Once there’s a plankton-rich environment, it’s time to fill the pond with fish. Kyaw stocks his ponds with what he calls babies, three-to-five-day-old fish acquired from a hatchery run by the government. “We are lucky that we are near the township office of the Department of Fisheries,” he says. After two months, the fish will have grown to two to four centimeters or so, at which point Kyaw moves them into the largest pond for the next year. He’ll shift them between ponds as needed over the three years it takes to raise the fish.

Wearing rubber boots, swim trunks, and a short-sleeved button-down shirt, Kyaw, sporting a bit of the belly that comes with middle age, surveys his ponds from a dike that separates them. When he started his farm, just out of school, business was tough. Today, however, it’s thriving—Kyaw and his wife have raised four children and sent them all to school on his income, with the oldest now in the third year of university. That’s not uncommon: aquaculture is so lucrative in Southeast Asia that few farms start with help from the government or international NGOs. Existing demand, market infrastructure, and local know-how are all they need. And their success creates a spillover effect: Kyaw employs about 10 people, a figure that can double seasonally. Research from the University of Georgia published in 2018 suggests that this is common, and significant since aquaculture performs better than terrestrial farming in terms of the income per hectare generated for the local economy. Aquaculture work typically pays better than agriculture work (though, as in virtually every other industry, women earn less than men), and is generally labor intensive. Operations employ a variety of laborers to dig the ponds; to feed, harvest, and transport the fish; to manufacture the fish food; and even to provide security. (Thieves are a continual menace, Kyaw says.) The FAO estimates that 20.5 million people worldwide work on fish farms, most of them for smallholders. Consumers come from surrounding towns to buy on the days Kyaw harvests, indicating that most of his production stays in Myanmar. “My product quality is well known,” he boasts.

Ko Kyaw Sein Tun with one of his employees rowing boat around his fish pond

Kyaw and one of his employees rowing around his fishpond in Pantanaw township, about 70 kilometers from Yangon. Photo by Htoo Tay Zar

One of the controversies that has dogged aquaculture is the issue of fish feed. A trade group, the Marine Ingredients Organisation, reports that about 12 percent of fish harvested from the wild goes to aquaculture. If fish from the ocean are going to feed those grown inland or in ocean pens, then aquaculture is contributing to the depletion of wild fish stocks, rather than diverting demand from them. But Kyaw feeds no marine products of any kind to his fish. Instead, his stock receives rice bran, a byproduct from one of the many local grain mills, which he mixes with beans. He supplements the mix with vitamins to promote growth, and antibiotics to prevent illness, which can sap his revenue. Antibiotic use is a dangerous practice in both aquaculture and agriculture. The World Health Organization has called their use in food production a significant threat to human health, fostering drug-resistant bacteria. Often, however, in a semi-intensive system, many farmers dispense with antibiotics, Belton says. He and his colleagues have found little use of antibiotics in Myanmar, based on their interviews with smallholders, while more intensive fish farming tends to see higher use of antibiotics.

Some fish farmers will rely on antibiotics, regardless of what they’re feeding their animals. Yet, few of the producers in countries with the most, and fastest-growing, aquaculture operations need much fish meal anymore. Although, according to scientific studies, Atlantic salmon can still get around 25 percent of their diet from fish meal, the formulation is generally falling out of favor. Fish meal is becoming more expensive and advances in feed manufacturing have enabled plant proteins to be included in the diets of carnivorous species. In places like Myanmar and Bangladesh, farmed fish eat mostly agricultural byproducts. Species commonly grown there—such as carp, tilapia, and catfish—are either omnivorous or herbivorous, and don’t need fish meal in their diet at all, Belton says. One common practice is to house poultry sheds over ponds, so the droppings can fertilize the ponds. Rice bran is abundant throughout Asia, as is oil cake, a byproduct from the manufacture of peanut or other oils. “Anything with caloric value can be used,” Belton says. “Waste from noodle manufacture, waste from MSG manufacture, canteen waste, brewery waste.” Meanwhile, processing waste from both capture fisheries and aquaculture is a growing ingredient in fish meal, potentially alleviating demand for wild-caught fish. Aquaculture, it turns out, can be a form of recycling.


Though the temperature is still above 25 ˚C and the sun high above the horizon, Kyaw sheds his straw hat for a moment as he oversees his employees. They are today’s link in a chain of fish farmers dating as far back as 6,600 years, when archaeological evidence suggests the Gunditjmara, an Indigenous people in Australia, were engineering channels from lakes and streams to raise eels. Around 475 BCE, a Chinese renaissance man named Fan Li wrote a guide to raising carp. Hundreds of years later, an emperor by the name of Li—the same word as common carp in Chinese—banned the farming of that species, which only served to spread the practice to other species. Romans and Egyptians also developed aquaculture techniques. By the 12th century CE, fish farming had expanded to India.

Employees at Ko Kyaw Sein Tun's fish farm

Employees at Kyaw’s fish farm drag nets to harvest fish in one of the operation’s 10 ponds. Photo by Htoo Tay Zar

Today, aquaculture is practiced on every continent save Antarctica. This is not without environmental impact, whether it’s shrimp and salmon or carp and tilapia. While closed, land-based aquaculture systems avoid some of the problems of ocean net-pen farms, their greenhouse gas emissions are greater (though still far below those of land-animal production). And, says Ruud Huurman, senior media advisor for anti-poverty NGO Oxfam Novib in the Netherlands, value continues to accumulate mainly with upstream producers and retailers in the Global North, where many retailers fail to answer for the environmental and working conditions of farms producing fish for export in southern or developing countries.

Whether these problems can be stemmed will be among the lines of inquiry of Belton’s next project. With funding from the US Agency for International Development’s Fish Innovation Lab, he will combine on-the-ground surveys of farms—painstaking work requiring hundreds of hours of interviews with farmers, some in remote locations—with remote sensing and artificial intelligence. Belton and his colleagues at WorldFish, a nonprofit research organization headquartered in Penang, Malaysia, where Belton lives, plan to analyze satellite photographs to look for known fish farms, and their characteristics, then feed the information into a computer capable of learning how to find farms in other images from around the world. Combining the data from the two sources, Belton and his team will develop the most accurate estimates yet of aquaculture production, employment, and economic value. The COVID-19 pandemic delayed the survey component, but Belton expects to conduct the necessary travel later this year.

The project’s aim is for policymakers and multilateral organizations, such as the FAO, to leverage the data collected to help them assess the potential of aquaculture to sustainably feed a growing population that’s becoming wealthier and seeking more protein. Whatever Belton finds, it seems freshwater aquaculture is here to stay. Demand is too great, and the return too alluring for new entrants. Operations like Kyaw’s could be one of the myriad of solutions that will be needed to feed 9.7 billion people in the coming decades.

Reporting from Myanmar by Htoo Tay Zar.

Read the final story in our special editorial package on aquaculture: “How to Stop Worrying and Love Farmed Fish

Big Fish

The Aquacultural Revolution