Trophic dynamics resilience of a characid fish in varied Amazonian stream landscapes

Context Knowledge of how fish species’ diets are influenced by local environmental changes is essential for their management and conservation. Aims We evaluated the effects of a wide range of land uses and physical-habitat attributes on the diets of Hyphessobrycon heterorhabdus populations. Methods We analysed the stomach contents of 253 flag tetra individuals collected from 26 stream sites (up to third order), with land uses raging from primary forest to bare soil. We also assessed channel morphology, hydrology, riparian vegetation and fish shelter. Key results We observed no significant influence of land use or physical habitat on fish populations’ diets. Instead, fish consumed a diverse set of allochthonous and autochthonous food sources, primarily Hymenoptera, termites and immature Diptera. These findings showed a generalist insectivorous diet. Conclusions The diet of H. heterorhabdus demonstrates remarkable adaptability to environment changes, which supports the high abundance of its populations. Implications Fish species with generalist diets, such as H. heterorhabdus, can both persist and thrive under a wide variety of environmental conditions.