LOOKING out from Mathabari, a village in northern Bangladesh, the landscape glints and ripples. Twenty years ago this was a rice-farming area, with fields of bright green. Now most of the land is covered with water. Carp, pangasius and tilapia swim in ponds separated by earth embankments. A few of the remaining patches of dry ground are occupied by sheds, where chickens are raised.

Shohel Matsay Khamar was one of the first in Mathabari to start farming fish. Since 2002 he has gradually rented more land from rice farmers, amassing about 70 acres (28 hectares). His is a forward-looking fish farm, with electric paddle wheels to keep the water oxygenated. He has even built a feed mill to grind maize, mustard oil cake and other raw materials into fish pellets. Cockroaches cover the walls, feeding on the nutritious dust.

Not only have Mr Khamar’s watery holdings expanded; he also gets more from each pond. He mostly farms pangasius, an unfussy silver-white fish, native to South-East Asia, which can breathe air. In the early years Mr Khamar would haul 20 tonnes from each acre of pond. Now, with better feed and cultivation methods, he gets about 40 tonnes. Poaching used to be a problem, he says, but not any more. Fish have become so plentiful and so cheap that nobody bothers.

In 2016 Bangladesh’s farmers produced 2.2m tonnes of fish (see chart). That is more than its fishermen caught in the wild, and more than fish farmers produced in any other country except China, India, Indonesia and Vietnam. The domestic farmed-fish industry has doubled in size since 2008 and is 19 times bigger than it was in 1984. Many things have helped it to grow, from aquaculture-research institutes to improved roads. But the main reason aquaculture is booming is that cities are booming, too.

A fish for all seasons

Farming and cities are usually thought of as separate poles. Each has its own ministries and budgets; charities often deal with one or the other. But cities can transform farming. Urban consumers represent a huge, fast-growing market for food, which may well be larger than a country’s export markets (not to mention less finicky about standards). Urbanites also have distinctive appetites. With more money than villagers and longer journeys to work, they favour tasty, quick-cooking, protein-rich fare. Sating their appetites is a huge job. Ben Belton, an expert on Asian aquaculture at Michigan State University, estimates that 94% of Bangladesh’s farmed fish are eaten domestically. Many are packed, wriggling or dead, into blue plastic barrels and driven to the cities. Urban Bangladeshis are thought to eat about one-third more fish per head than rural folk. And there are ever more urban heads. Dhaka, which is 95km south of Mathabari along a good road, already contains some 20m people. UN statisticians think it is growing by more than half a million a year.

The task of feeding that huge population has not been accomplished by the government, by charities or by foreign agricultural investors. It is the work of an army of ordinary Bangladeshis with an eye for making money. Mr Belton’s research shows that the number of fish-feed dealers in the main aquaculture areas more than doubled between 2004 and 2014. So did the number of feed mills and fish hatcheries. Mr Belton has found similar trends in Myanmar, where the fish farms are often larger than in Bangladesh, and in India.

As well as transforming landscapes in a large radius around Dhaka, the fish boom has changed many people’s lives. Aquaculture requires about twice as much labour per acre as rice farming, and the demand is year-round. Many labourers who used to be paid by the day are now hired for months at a time. Seasonal hunger, which is a feature of life in some rice-farming regions of Bangladesh, is rarer in the watery districts. People are eating more protein. Mohammad Shafiqul Islam, a feed dealer, points to another advantage. Because food is now so cheap in the cities, migrant workers are able to send more money back to their families in the villages.

The rock-bottom prices that so delight consumers make life hard for producers. The past year has been especially bad, partly because of flooding in northern Bangladesh, which drove up the cost of rice and left consumers with less money to spend on fish. Mr Khamar says he has been selling pangasius for between 65 takas ($0.78) and 80 takas per kilo, down from more than 100 a year ago. But his main problem is that the market is oversupplied. In effect, he is a victim of his fellow-farmers’ success. That problem is not specific to aquaculture, or to Bangladesh.

About two hours’ drive north of Nigeria’s commercial capital, Lagos, is a business called AOD Farms. It began in 2009 as an egg-producing operation with some 1,500 hens. But the residents of Ogere, the small town where the business was located, complained about the smell. So AOD Farms moved to the outskirts and started raising chickens for meat, known as broilers. It now has around 10,000 birds at any time. In the run-up to Christmas it adds a few hundred turkeys and cockerels.

Count your chickens

AOD Farms is part of a white-meat explosion that rivals the fishy one. Saweda Liverpool-Tasie, an agricultural economist at Michigan State University, calculates that there are now around 1,000 medium and large poultry farms in Nigeria, up from around 400 during much of the 1990s and 2000s. The quantity of maize used for feed shot up from 300,000 tonnes to 1.8m tonnes between 2003 and 2015. There is little reason to expect growth to slow down. The average Nigerian still eats only about two chickens a year.

In some ways the west African chicken boom is different from the Asian fish boom. Whereas Asian fish farmers are often former rice farmers, African poultry farmers are more likely to be wealthy, well-connected urbanites. AOD Farms is owned by a civil engineer. Nigeria’s former president, Olusegun Obasanjo, has a large poultry business in the south-west. Foreign investors play a large role, too. Last September Olam, a multinational agribusiness firm listed in Singapore, opened two large feed mills in Nigeria. One of them will also produce fish food.

But the parallels are more striking than the differences. As with fish in Bangladesh, the Nigerian chicken industry clusters around the fast-growing largest city. Lagos is estimated to have between 12m and 15m inhabitants, though it is hard to be sure as Nigerian population data are notoriously unreliable. Lagosians’ hunger can certainly be felt in Ogere. AOD Farms sells many chickens at the gate to local buyers. Of the ones that are loaded onto trucks and driven away, 70% go to Lagos.

Coming home to roast

In both countries the industries are becoming more professional. Bangladeshi fish farmers increasingly use medicines and floating fish feed, which is less wasteful than the sinking kind. AOD Farms is still a dusty work in progress—during a recent visit, some chickens had escaped through a hole in the fence. But a vet comes at least once a week and the farm manager, Kunle Adebayo, studied agriculture and business at university. Larger, slicker firms sell chicks and veterinary services to smaller outfits.

In a final parallel, farmers in both Nigeria and Bangladesh complain bitterly about excessive supply. Nigerian chicken farmers insist that the domestic market has been flooded by foreign investors and foreign chickens. The Poultry Association of Nigeria claims that about 70% of the birds eaten in the country are illegally imported. However, Ms Liverpool-Tasie reckons that only 15% are imported. Chicken farmers’ profit margins have probably been kept thin by the rising price of feed and a surge in domestic production.

It is hard to know for sure, though, because official statistics are so poor. Chicken and fish farmers have little idea what their competitors are producing, so they find it hard to predict what price their produce might fetch at market. Mohammad Mahfujul Haque, an aquaculture expert at Bangladesh Agricultural University, argues that detailed annual figures on fish production would help enormously. Bangladesh already does this for crops.

So would a certification system. At present, a chicken is just a chicken and a pangasius is simply a pangasius. That prevents farmers from exporting to rich countries, where consumers insist on knowing where their food comes from and how it is produced. The lack of standards even causes problems at home. In place of real information, Bangladesh has rumours. In a few days your correspondent heard two. One was that pangasius are toxic; the other that the first rumour had been spread by traders in an attempt to suppress prices. Both appeared to be nonsense.

But the pressure on farmers is making them inventive. In a warehouse in Mymensingh, a town close to Mathabari, Shamsul Alam has installed eight large vats. When he shines his torch in, they are revealed to contain thousands of stinging catfish. Although the fish is tricky to handle, owing to the venom in its dorsal spines, it is a delicacy that fetches at least four times as much as pangasius per kilo. The water in the vats is cleaned by a machine imported from Canada.

It is an expensive, technically complex way of farming fish. The indoor fish farm poses no competitive threat to open-air farmers. Still, Mr Alam’s innovation is an intriguing way of coping with persistent low prices for the most common fish. He says that one of his neighbours is already copying him.

However much farmers struggle with the consequences of their success, it is a far nicer problem than the one they used to grapple with. Walking down a market street, Mr Haque dips his hand into a sack of maize and a sack of rice. The grains will be bought by farmers, who will grind them into pellets for fish and cattle. “Twenty-five years ago, people were starving for want of this,” he says, marvelling. “Now we feed it to animals.”