Abstract
Feeding ecology underpins the functional role of fish species within riverine food webs and determines the trophic
linkages that regulate energy flow and nutrient cycling in freshwater ecosystems. Tropical rivers, characterised by high
fish diversity, strong seasonal hydrological variability, and complex lateral connectivity between river channels and
floodplain habitats, present distinctive feeding ecology challenges and opportunities for diverse fish communities. This
study examines the feeding ecology of 84 freshwater fish species from the Godavari and Krishna river systems of
peninsular India, using stomach content analysis, stable isotope analysis (delta13C and delta15N), and functional trait
assessment at 18 sites sampled during monsoon flood and dry season low-flow periods over two years (2021-2023).
Fish species are classified into eight feeding guilds based on stomach content analysis. Piscivores and invertivores
dominate in terms of biomass contribution; algal grazers and detritivores are most species-rich. Stable isotope analysis
reveals significant seasonal shifts in diet composition, with 38.4% of species showing ontogenetic diet shifts from
invertivory to piscivory or herbivory. Invasive tilapia (Oreochromis niloticus) occupies a broad trophic niche that overlaps
significantly with native species, with measured trophic overlap values exceeding 0.7 for 12 native species. Conservation
implications of trophic disruption by invasive species and by water quality changes affecting food web structure are
discussed.