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Four combinations of fish and prawn species were stocked in organic rice–fish systems to examine their growth performance, feeding habits, competitive interactions, and food-web structure. The species combinations were: (I) three fish species commonly stocked in rice–fish systems in the Lower Mekong countries, namely Barbonymus gonionotus, Cyprinus carpio, and Oreochromis niloticus; (II) the same three species plus the giant freshwater prawn Macrobrachium rosenbergii; (III) three herbivorous fishes native to the Mekong River, namely B. gonionotus, Barbonymus schwanenfeldii, and Cirrhinus microlepis; and (IV) the herbivorous and omnivorous fishes B. gonionotus, C. microlepis, and Trichogaster pectoralis, together with the carnivorous fish Channa striata. Growth performance was examined using specific growth rate (SGR), and feeding habit was examined through stomach content and stable isotope (carbon and nitrogen) analyses. All fish and prawn species exhibited SGRs of roughly 1–2% d−1 except for C. striata, which had a slower growth rate (

The potential of catch per unit effort (CPUE) analysis based on statistics of local fisheries in Tonle Sap Lake in Cambodia was evaluated. The fishery statistics system was improved through a cooperative project conducted by the Department of Fisheries and the Mekong River Commission between 1994 and 2000, especially in the seven provinces adjacent to Tonle Sap Lake. However, the fisheries statistics were not effectively utilized for sustainable stock management. After the cooperative project, fish catch data sorted by species or species group were collected at the province level in the seven provinces. Another recent project also revealed the numbers of fishing gears that operated in the seven provinces. The CPUEs of ten species in Kampong Thom Province—including Channa micropeltes and Cirrhinus spp.—could be calculated from 1994 to 2007, because these are caught solely using bamboo fence systems or barrages. CPUE analysis clarified that stocks of high-price fishes such as Ch. micropeltes, Hampala spp., and Pangasius spp. have deteriorated while those of relatively low-price fishes such as Cirrhinus spp., Cirrhinus microlepis, Cyclocheilichthys enoplos, and Channa striata have increased in recent decades.