People have been farming fish for thousands of years. The Chinese raised fish in ponds some 3 000 years ago; the Romans farmed oysters in shallow coastal bays; and mediaeval monks in Europe reared fish on table scraps in ponds fertilized with human waste.

Today aquaculture has become big business in Asia, Latin America, North America and Europe. Smaller-scale activities, raising fish in village ponds, also take place in some sub-Saharan African countries and in Asia, while Thai, Indonesian, Chinese, Malaysian and Filippino farmers also farm fish in rice paddies for their own consumption.

These enterprises - whether in large ponds, in sea cages or in tiny backyard ponds - hold much promise for meeting increasing food demands. In fact, with most capture fisheries in decline, aquaculture is the best way to maintain and increase supplies of saltwater and freshwater fish.

Fish farming expanded greatly between 1984 and 1993, growing at an average rate of 9 percent a year. In 1993, aquaculture produced 22.6 million tonnes of fish, shellfish, invertebrates and plants (mostly seaweed), worth US$ 35 708 million. It contributes 16 percent to global fisheries production, compared to just over 8 percent in 1984. Over half of all freshwater fish production comes from aquaculture.

Asia accounted for nearly 87 percent of the world's fish farming output in 1993: 63 percent of its share was produced by China, with India as the next biggest contributor.

The industry is overwhelmingly concentrated in the developing world, which accounts for 85 percent of output by volume and 71 percent by value. Exports of high-value species such as shrimp, prawns and salmon earn much-needed foreign currency for these countries. Fish farming may increasingly be the only way for some poor communities, who rely on fish and shellfish for the bulk of their protein intake, to maintain a healthy diet.

In spite of this promise, aquaculture projects are vulnerable to disease and environmental problems. Overstocking and pollution have devastated some Asian and Latin American freshwater operations. Marine aquaculture is constrained by the rising pollution of coastal waters. Nutrient and organic over-enrichment, the accumulation of toxic chemicals, microbial contamination, siltation and sedimentation all jeopardize expansion. Where aquaculture results in the degradation of coastal mangroves, the breeding grounds of many wild species, it poses a major threat to biological diversity.

Better selection of production sites to safeguard the environment and sound management techniques can overcome most of these difficulties. FAO expects aquaculture's output to double in volume within the next 15 years.

The growth of aquaculture

Total global aquaculture production in 1993

Inland fisheries and aquaculture

	The cultivation of carp has a long tradition, particularly in Europe and Asia. They still dominate aquaculture, accounting for most of the fish production. For home ponds they have the advantage of being non-carnivorous and so not requiring expensive protein-rich foods.
	Tilapia, the mainstay of small-scale aquaculture for many poor farmers, have spread far from their original African home. Dubbed "the aquatic chicken" they are most widely farmed in Asia, particularly China. the Philippines and Thailand.
	About half of the annual harvest of shrimp - a high value export product comes from aquaculture. Progress in the production of shrimp over the past 10 years has been largely responsible for a fourfold increase in the annual harvest of crustaceans.

Top aquaculture producers

Top eleven aquaculture producers, 1993