Diversity of fish fauna and water quality in the downstream of Batang Ai HEp, Engkilili, Sarawak

This research was conducted to document the diversity of fish fauna and fish composition along with selected water quality parameters in the downstream of Batang Ai HEP, Engkilili, Sarawak due to lack of infonnation on fish fauna in the downstream area of the hydroelectric power plant. Ten stations were selected for fish sampling and four stations for water quality parameters. Fishes were sampled using monofilament gill nets of different mesh sizes and three-layered nets. A total of 67 individuals were caught from all stations with Cyprinidae as the dominant family (40.30 %), followed by the families Siluridae (19.40 %), Bagridae (11.94 %), Toxotidae (8.96 %), Ariidae (4.48 %), Sciaenidae (2.99 %), Osphronemidae (2.99 %), Syngnathidae (1.49 %), Mugilidae (1.49 %), Datnioidae (1.49 %), Polynemidae (1.49 %), Carangidae (1.49 %) and Megalopidae (1.49 %). The six dominant species recorded were Kryptoptenls parvanalis with 13 individuals, followed by Hampala macrolepidota (10 individuals), Barbonymlls schwanenfeldii (9 individuals), Hemibagms planiceps (8 individuals), Toxotes microlepis (6 individuals) and Cyclocheilichthys apogon (6 individuals). Species diversity, species richness and species evenness values were higher during dry season which were 2.2990, 3.6831 and 0.6213, respectively as compared to wet season with species diversity, species richness and evenness of 2.1752, 2.9621 and 0.6068, respectively. Water quality results showed that temperature ranged from 27.66 °C to 28.82 °C, conductivity ranged from 23.09 JlS/cm to 24.63 JlS/cm, pH ranged from 6.71 to 7.03, turbidity ranged from 0.84 NTU to 7.95 NTU, dissolved oxygen ranged from 5.20 mglL to 7.20 mg/L, transparency ranged from 0.80 m to 1.35 m, BODs ranged from 4.67 mglL to 9.80 mglL, chlorophyll-a ranged from 0.00102 mg/L to 0.01863 mglL, and total suspended solids ranged from 4.87 mglL to 29.00 mgIL. The population of fish in the downstream of Batang Ai Hydroelectric Power Plant showed relatively low number of individuals caught. Therefore, the fish assemblage in the downstream was impacted by the impoundment of hydroelectric power plant