Rice and fish
It is suggested that fish culture in rice fields was introduced into Southeast Asia from India about 1500 years (some reported 2000 years) ago, where presently it is the best developed. Rice-fish culture is well established in other paddy (rice) growing countries, especially in Taiwan and Japan. It can be a low-cost, low-risk option for poor rice farmers in rice-farming countries, including Malawi, Bangladesh, China, India, Indonesia, Korea, Laos, Madagascar, Malaysia, the Philippines, Thailand, Cambodia, and Vietnam.
There are a number of advantages to integrated rice-fish cultivation. The presence of fish in a rice field generally increases the rice yield by 10 to 15%. By cultivating two products farmers decrease the risk of loss if one crop fails. Fish is a source of protein, and by integrating production with rice farmers can improve their own food security. Fish also sometimes eat the animals which transfer diseases to people, so raising them can improve public health. Some fish species, such as the common carp eat mosquito larvae and snails which spread disease. Raising fish in a rice field is also a biological way of reducing weeds, insects, snails and some rice diseases. This is a safe and cheap alternative to using chemical pesticides to control insects and algae.
However, this beneficial cultivation system was gradually abandoned due to population pressures, decreasing stocks of wild fish and the "Green Revolution" which emphasized high-input monoculture using high-yield rice varieties, pesticides, and herbicides (which are toxic to fish). During the 1980s and early 1990s, rice-fish culture as managed cultivation systems experienced a revival, as concerns over the widespread use of pesticides emerged.
Rice and fish production do not need to be integrated by always producing the two crops simultaneously, but may be done by alternating production: rice can be grown in the rainy season and fish in the dry season, or the other way round. By not raising the two together, it is easier to control the water level so that it is right for both rice and fish. In areas where rice production is not profitable in all seasons, fish production forms an alternative source of income from the field.
Other integrated fish-rice culture systems
There are many different methods of rice-fish culture, which vary in types of trenches used, stocking rates, fish species used, and supplemental feeding. It is important to base rice-fish culture on local farmers' current cultivation methods. Sometimes, they can be combined with keeping other animals.
In Thailand, an integrated system of pig, rice and fish culture is practised. The fish pond is linked to the rice field. During the rainy season the rice field is fertilized using water containing pig manure from the fish pond. The water in the fish pond is used during the dry season to water vegetables or rice seedlings in the rice field.
In China and Indonesia, rice, ducks and fish are raised together. The ducks are fed with rice in the evenings. The ducks also eat insects and snails from the rice fields, which means it is not necessary to purchase expensive chemical pesticides. The water in the rice field is 10-15 cm deep and the rice plants are planted 25cm apart so that ducks can swim around freely. A rice field of 100 m² can sustain 30 ducks, which can be introduced when they are between 7 and 10 days old. Manure from the ducks and the fish fertilizes the rice field, so that artificial fertilizer does not have to be bought. Ducks raised in rice fields grow more quickly than ducks which kept on land. They reach a weight of about 1kg after about six weeks. At this point they should be removed from the rice field as they no longer eat insects and will start to eat the rice plants.
In Indonesia, the dykes around rice fields and fish ponds are used to grow trees. Sesbania trees are planted at intervals of 40 cm on the dykes. Over a period of three years the following products can be harvested: leaves and flowers for human consumption and animal feed, large branches for firewood and shade for people and animals.
In Bangladesh trees are planted on the dykes of rice fields for firewood. Species used include Eucalyotus camldulensis, Swietenia macrophylly and rosewood, ladyfinger, ridge gourd, ash guard and papaya.
Diversity in the food system
Introducing fish in rice paddies helps to control pests and provides an additional source of income and nutrients to farmers.
Images for rice-fish culture