19. Rice/fish farming in Malaysia: a resource optimization
AMBIO, 19, 8, 1990, pp. 404-407
This paper summarizes and discusses the ecology as well as rice/fish farming system as practiced in North Kerian, Perak, Malaysia.
In Malaysia, where arable land is limited, integrated farming systems are widely practiced to optimize land use. Integrated rice/capture-fish farming is an example and is an important source of freshwater fish.
Capture-fish farming is practiced in North Kerian, Perak, Malaysia, where wild fish are retained and grown in the rice fields and later harvested at the end of the rice-growing season. Sump ponds, dug at the lowest part of the rice fields, provide refuges for fish during periods of low water availability or quality and facilitate fish harvest.
Before the early 1970s, when single cropping of rice was practiced, the system was the major supplier of freshwater fish, especially snakeskin gouramy (Trichogaster pectoralis), catfish (Clarias macrocephalus), and snakehead (Channa striata). But when double cropping of rice began in the 1970s followed by the widespread use of herbicides and pesticides, fish harvest began to decline.
The system described here requires no biological and little economic input, and native fish are found to be both biologically and economically suitable. The system can utilize different specific habitats, the fish are tolerant to extreme physiochemical changes, and command good market prices. The different feeding habits of the predatory snakehead (Channa striata), omnivorous catfish (Clarias macrocephalus), insectivorous climbing perch (Anabas testudineus), and plantivorous-omnivorous gouramies (Trichogaster pectoralis and T. trichopterus) indicate possible yield improvements through rice/fish polyculture. Aquatic productivity of the prevailing ecosystem is low despite repeated seasonal fertilization. Productivity is probably low due to shading and competition with aquatic weeds and rice plants.
Zooplankton is not readily available to the fish larvae and fingerlings because aquatic weeds provide easy refuge. This lack of food results in fish below marketable size. The short growing season resulting from double cropping, coupled with widespread use of herbicides and pesticides, also affects fish production.
The shorter growing due to double cropping of rice cannot be avoided since it is the policy of the government to increase rice yields.
Increasing the system's productivity is the only way to increase fish yields.
Integration of other farming activities into the rice/fish-capture farming system are being tried in order to fully optimize land use.
Extra income could be obtained by properly planting the large dikes surrounding sump ponds with valuable fruit trees such as coconuts (Cocos nucifera), bananas (Musa spp.) and mangoes (Mangifera spp.).
Farmers also planted the perimeter dikes with produce such as tapioca (Manihot spp.),squash (Cucurbita spp.), and sweet potato (Ipomea batatas) that can either be used at home or sold at the local market.
These and other activities are a recent addition to the traditional rice/fish-farming system and further investigations should be undertaken to determine their economic feasibility.
1088 92 - 3/138
Review, fishfarms, farming, biotechnology, transgenic fish, aquacultural genetics, feed conversion, environmental impact
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