Diet composition and trophic guild structure of fish assemblage in headwaters of the Chishui River, a tributary of the upper Yangtze River, China

In this study, the diet composition and trophic structure of the fish assemblage in the headwaters of the Chishui River were investigated. A total of 1677 fish specimens belonging to 14 species were collected and dissected. Of these specimens, 1063 individuals with undigested food in their stomachs or guts were used for analysis. Our analysis identified thirty-one kinds of prey, which were classified into eight categories, namely, diatoms, chlorophytes, other vegetable prey, aquatic insects, mollusks, other invertebrates, fishes, and unidentified organic matters. Among these categories, diatoms were the most important prey for this fish assemblage. With an ontogenetic dietary shift, the 14 species were subdivided into 16 predator groups, which were categorized into five trophic guilds, namely, algivore (diatoms), algivore (chlorophytes), omnivore, aquatic insectivore, and piscivore. Their diet composition significantly differed from one guild to another ( p