Rice-fish is an integrated farming system with a long history in the region. Asian farmers have been raising fish in the rice fields for 2,000 years, perhaps even longer, providing farm families with an important source of animal protein. Originally, wild fish bred naturally in the rice fields, and were harvested as opportunity provided. Over time, a variety of husbandry techniques evolved in many countries of the region. But with increased population pressure, the advent of “high-yielding” rice varieties, and the consequent emphasis of governments and researchers on high input rice monoculture, these traditional technologies have often been left behind. In particular, the heavy use of pesticides and herbicides, most of which are toxic to fish, has made fish culture impractical in many rice farming situations. Many farm families have been deprived of this important source of nutrition – one not recognized by research planners in the past. In the past decade, considerable interest in rice-fish has arisen among researchers and, more important, farmers, as the pressure on farm ESOUK~S has increased. The need for more efficient and more sustainable farming systems has led to a variety of rice-fish farming systems in almost all countries of the Asian region. Many research institutions and donor agencies are recognizing the importance of this development, and a number of important research activities are underway, in farmers fields and on research stations. For example, the Sukamandi Research Institute for Food Crops and the Indonesian Research Institute for Freshwater Fisheries are collaborating in an IDRC-sponsored project begun in 1987. The aim of the project is to raise the visibility of rice-fish farming to Indonesian farmers and government policymakers alike.
The research has on-station components, attempting to understand ecological and other interactions of rice-fish systems, and experiments in actual producing farms to understand and adapt to the real constraints and opporrunities faced by farmers. To begin a rice-fish operation, the farmer digs a small pond or trench about 0.5-l metre deep in a low-lying area of the rice field, to act as a deeper water “refuge” for the fish. The excavated soil is used to raise the “bunds” or banks of the field to ensure good water control (and in the process creating a raised area above flood level, often suitable for planting other crops like vegetables and fruit trees). When the field is flooded by irrigation water (or by rains, as in Northeast Thailand) rice is planted as usual. Soon after, however, small fish fingerlings are introduced. In Indonesia, the most frequently used fish are common carp (Cuprinus carpio) and other local carps, but tilapia, catfish, and several other species are commonly found in rice-fish farms. After a short period of up to 3 weeks, during which the rice plants become well established, the fish are let out of the refuge and allowed to forage through the rice fields. At harvest time, or if the fish must be temporarily removed while some potentially toxic chemical is applied to the field, the water is drained down and the fish are collected from the refuge. This simultaneous culture of fish in rice fields is called “minapadi” in Indonesia, and is the most interesting from a potential productivity point of view. Rotational (“palawidja ikan”) and sequential (“ikan penyalang”) systems of rice-fish intercropping are also found. The synergistic effects of rice and fish in the same field exemplify the advantages of an integrated approach to farming. One of the key benefits in this case is that fish recycle nutriens through feeding and depositing their fees in the submerged soil. Initial research results indicate that uptake of important nutrients like phosphorus and nitrogen by the rice plants is significantly improved, in comparison with rice monoculture. Dr Achmad Fagi, the leader of the Indonesian project, found that “rice-fish culture with common carp actually increased the yields of commonly used rice varieties.” Farmers can in many cases get better rice yields plus additional food and cash income in the form of fish.