Abstract

• Rice-fish systems can be broadly defined as the cultivation of rice alongside the simultaneous or rotational presence of naturally occurring fish and other aquatic species that are harvested through fisheries, as well as introduced fish populations that are cultured. Fish species are vital for maintaining ecological health and are also economically important for human consumption. In this study, the seasonal variation of heavy metal concentrations (As , Cd and Pb) which bio accumulated in muscle tissues of three fish species (Catla catla, Labeo rohita, Puntius gonionotous) cultured in the rice-fish farm located at West Tarpet Village, Maubin Township were analyzed. Seasonal variation of metal concentrations in water and soil from rice- fish farm were also investigated during the study period. The concentrations of heavy metals in collected specimens were analyzed in the Universities’ Research Center (URC) at University of Yangon. The levels of metal concentrations varied depending on the seasons and the different fish species. The highest concentration of As was found in Catla catla in the cold season and Cd in Puntius gonionotus in the hot season but the results did not exceed the WHO/FAO maximum permissible limits. Pb concentration of Catla catla in the rainy season was found to be the highest and over- established by WHO/FAO. The Cd and Pb concentrations of river water were highest in the hot season and in the rainy season; the results were higher than WHO/FAO. The average concentration of Pb in the rainy season of soil sample was the highest and observed to be beyond the WHO/ FAO limit. Based on the results of the present study, the concentration levels of Pb in soil, water samples and, Catla catla, as well as Cd in river water exceeded the acceptable limits recommended by WHO/FAO. Significant relations between As and Cd concentrations in the muscle tissue of the fish species and their size (total length) and (body weight) were observed. According to the results of the transfer factor, all tested metals accumulated in muscle tissues of studied fish species came from their abiotic media. The concentration of heavy metals in muscle tissues of Labeo rohita and Puntius gonionotus were not exceed the permissible limit of WHO/FAO, 2011 and there was no a risk for the public by eating these species.