Use of wastewater from striped catfish (Pangasianodon hypophthalmus) pond culture for integrated rice-fish-vegetable farming systems in the Mekong Delta, Vietnam

This article investigates the feasibility of reusing wastewater from striped catfish (Pangasianodon hypophthalmus) pond culture as nutrient input for integrated rice–Nile tilapia–green bean farming systems, and to what extent this could contribute to decreasing the environmental impacts on water quality from the striped catfish industry in the Mekong Delta. Four treatments in triplicates were used to investigate the growth of rice and green bean varieties under different combinations of inorganic fertilizer and water from the river and a striped catfish pond culture. The Nile tilapia (Oreochromis niloticus) was cultured at low density without feeding in a canal adjacent to the rice field. Rice yields ranged from 3,514 to 4,023 kg ha−1 with no significant differences between treatments (p > 0.05). The yield of green bean ranged from 2,671 to 3,282 kg ha−1 (p < 0.05), with the highest yields for beans only receiving water from the striped catfish pond. The water quality concentrations decreased significantly when passing through the rice plots for almost all treatments (p < 0.05). Total phosphorus and nitrogen levels in the outflowing water were reduced by almost 50% compared to the inflowing water from the striped catfish pond. Overall, the results indicated that an integrated system generates both economic and environmental benefits as compared to monocultures.