For the first time in modern history, the world farmed fish production has toppled beef production with annual fish production in 2013 reaching 66 million tonnes compared to beef’s 63 million tones.

But fish consumption in Kenya is dismally low by international standards with each Kenyan consuming on average 2.8kgs of fish yearly compared to the worldwide average of 16kgs. Fish contributes 11 percent of average daily protein consumption throughout the country.

Historically, as the global demand for animal protein grew more than fivefold over the second half of the twentieth century, humans began to press against the productivity constraints of the world’s rangelands and oceans. Annual beef production climbed from 19 million tons in 1950 to more than 50 million tons in the late 1980s. Over the same period, the wild fish catch ballooned from 17 million tons to close to 90 million tons. But since the late 1980s, the growth in beef production has slowed, and the reported wild fish catch has remained essentially flat.

Historically, people’s taste in eating animal protein was largely shaped by where they lived. In places with extensive grasslands, like in the United States, Brazil, Argentina, and Australia, people gravitated toward grazing livestock. Along coasts and on islands, as in Japan, wild fish tended to be the protein staple. Today, with little room for expanding the output from rangelands and the seas, producing more beef and fish for a growing and increasingly affluent world population has meant relying on feedlots for fattening cattle and on ponds, nets, and pens for growing fish.

While open waters and grasslands can be self-sustaining if managed carefully, raising fish and livestock in concentrated operations requires inputs. Grain and soybeans have been inserted into the protein production food chain. Cattle consume 7 pounds of grain or more to produce an additional pound of beef. This is twice as high as the grain rations for pigs, and over three times those of poultry. Fish are far more efficient, typically taking less than 2 pounds of feed to add another pound of weight.

Pork and poultry are the most widely eaten forms of animal protein worldwide, but farmed fish output is increasing the fastest. Average annual growth rates over the last five years have mirrored the relative efficiency of feed use, with the global production of farmed fish growing by nearly 6 percent a year, poultry by 4 percent, and pork by 1.7 percent—fast outpacing beef, which barely increased at all.

As grain and soybean prices have risen well above historical levels in recent years, the cost of producing grain-eating livestock has also gone up. Higher prices have nudged consumers away from the least-efficient feeders. This means more farmed fish and less beef. In the United States, where the amount of meat in peoples’ diets has been falling since 2004, average consumption of beef per person has dropped by more than 13 percent and that of chicken by 5 percent. U.S. fish consumption has also dropped, but just by 2 percent.

Beyond economic considerations, health and environmental concerns are also leading many people in industrial countries to reduce their beef intake. Meanwhile, fish are touted as healthy alternatives (save for the largest types, which have accumulated mercury from environmental pollution). Diets heavy in red meat have been associated with a higher risk for heart disease and colon cancer, among other ailments.

Beef production has garnered a negative reputation for having a large carbon footprint and for destroying habitat, notably in the Brazilian Amazon. And excess nitrogen fertilizer applied to the fields of feed corn grown to satisfy the world’s livestock runs off into streams and rivers, sometimes flowing to coastal waters where it creates large algal blooms and low-oxygen “dead zones” where fish cannot survive.

While it is only recently that the limitations of natural systems have emerged on a global scale, the practice of aquaculture dates back millennia. China, which accounts for 62 percent of the world’s farmed fish, has long cultivated different types of carp that eat different things—phytoplankton, zooplankton, grass, or detritus—together in a mini ecosystem. Today carp and their relatives are still the mainstay of Chinese aquaculture, making up nearly half the country’s output. Filter-feeding mollusks, like clams and oysters, account for close to a third. Carp, catfish, and other species are also grown in Chinese rice paddies, where their waste can fertilize the grain crop. This is also practiced in Indonesia, Thailand, and Egypt.