PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Study on fish diversity and distribution in rice plots supplied with recycled and uncontrolled flow water was carried out from Season 1/2002 to Season II/2004 (August, 2002 to August, 2004) using a modified electro-shocker. A total of 13 species of fish were identified, with Cyprinidae being the dominant family in terms of the number caught (39.5%), followed by Aplocheilidae (18.2%), and Osphronemidae (12.0%). The number of species identified was lower as compared to those obtained in previous studies at selected irrigation canals in the Muda agro-ecosystem, and this due to different methodology employed. In the rice field plots irrigated by uncontrolled water flow, 13 species were recorded, whereas only 11 species were recorded in the plots irrigated by recycled water. However, based on the Shannon-Weiner Diversity and Evenness Indices, the values for the recycled water plots were higher (0.8764 and 0.8416, respectively) compared to the values obtained for the uncontrolled flow plots (0.8131 and 0.7300, respectively). The clustering analysis showed that the similarity in term of the fish species in both plots is high at 0.8462. In particular, Esomus metallicus was the dominant “species catch” (36.4%), followed by Aplocheilus panchax (18.2%) and Anabas testudineus (10.6%). Most of the species identified were well-adapted to survive under the extreme conditions of the rice fields, such as the lower and higher D.O. and water temperature readings of 0.3-14.8 mg/L and 14.0-41.0°C, respectively. However, floods that occurred in Season 1/2004 were found to have influenced the fish diversity as some riverine species, such as Barbodes gonionotus and Cyclocheilichthys apogon, were caught in the studied rice field plots.