ANALYSIS ON THE FEEDING HABITS OF HEMICULTER TCHANGI

miculter tchangi Fang is an endemic fish in the upper Yangtze River, and mainly distribute in Sichuan Province and Chongqing City. At present, more and more researches have used endemic fish as indicative species to appraise the healthy of the river which they lived. Further more, the habitat changed dramatically due to the construction of a series of hydroelectricity projects, it was forecasted that the population sizes of the endemic fish might decreased sharply in the future. It is very urgent to make suitable countermeasures for the conservation and resource-recovery of those endemic species. This paper preliminarily analyzed the diet composition and its variation over seasons, years and different developmental phases of gonad. 72 specimens were collected from the estuary of the Chishui River, the first-order tributary of the Yangtze River, which locating at Hejiang county of Sichuan Province. The contents of the alimentary tracts of H. tchangi were analyzed to establish diet composition. The results indicated that H. tchangi was omnivore-fish stressing on animality. The diet compositions of H. tchangi included dipterans (i.e. larval mosquito and fly), plants and their seed, algae, oligochaeta (i.e. freshwater earthworm), hymenopterans, crustacean, cladocera, cole-opteran, mollusks, small fish, fish eggs, larva frog and so on. Dipterans, plants and their seed, algae were the most im-portant groups according to occurrence ratio. Variation in food composition among sampling sites was high. This high variation appears to be primarily associated with differences in prey availability, but much less with prey size selectivity. Feeding intensity varied considerably among seasons. The occurrence frequency of animal bait reached to its highest in summer, whereas the peak of algae was in winter. The highest food fillness and feeding rate appeared in spring when energy-rich food was needed for the final maturation of gonads, while the lowest appeared in autumn. This was mainly because that the metabolism and motility of fish was much higher than other seasons when the water temperature and the richness of food were in the highest status. The feeding rate increased with age growing from 1 to 4. This phe-nomenon suggested that the predation capability grew with age and body-length growing. But the food fillness did not take on such regular changing pattern. The relationship between food fillness, feeding rate and different developmental phases of gonad of this fish were as follows: the food fillness was much higher in phrase than other gonad develoⅡp-mental phases to the female, while there was no such phenomenon to the male. This was mainly because that the female need much energy to propagate. The fish feed in the propagated period too. But the food fillness and feeding rate were both in the medium state in the reproductive stage. The phenomenon that H. tchangi is an omnivore preying on terres-trial insects was emphasized. It was hypothesized that the outer of terrestrial insects were covered with chitin shell, so they can not be easily digested in a particular time span, often leaved compounded eyes, appendage and so on. These materials are obvious indicators that can be easily found and observed under the microscope. To be contrast, the species which lived in freshwater, like freshwater earthworm and larval mosquito, have no such strong protection all over the body, so they were digested more easily by predators without any body parts left. After the construction of several dams, the former flowing water became stable and slow. This may affect the feeding habit and the living situation of H. tchangi.