EVALUATION OF FISH FEEDING HABITS AND TROPHIC POSITION IN BUKIT MERAH RESERVOIR, PERAK, MALAYSIA: PRELIMINARY ANALYSIS USING STABLE ISOTOPE ANALYSIS AND GUT CONTENT ANALYSIS

Monitoring feeding habits and Trophic Position (TP) is crucial for the timely response to ecological predicaments like agricultural intensification at upper runoffs of Bukit Merah Reservoir (BMR). Selected fish samples were evaluated for feeding habits and TP using stable isotopes analysis (SIA) (δ13C and δ15N) and gut content analysis (GCA). Cyprinidae comprised 91% of the total samples. No significant differences in δ13C among fish feeding habits (p > 0.05) showed that fish consumed similar basal carbon sources derived from C3 photosynthesis pathways. Significant differences were found between δ15N values and the interactive effect of fish feeding habits (p < 0.05) with carnivorous fish recording the highest median score (Md = 2.62). Hampala macrolepidota (TP = 2.73) and Mytus singaringan (TP = 2.50) occupied the highest position in the food web. Detritus was the main food source for BMR fish (44%), showing a high degree of omnivory. The gut content of Barbonymous gonionotus and Larbiobabus leptopcheilus was the most diverse, indicating a wide range of food consumption. Fish samples that inhabit the BMR food web are favoured as detritivores or omnivores. This study provides the baseline data on the fish diet composition and their TP, which will be useful for future modelling uses in BMR fish management and conservation.