Abstract: A total of 547 specimens of Rhinogobio cylindricus were monthly collected from the upper reaches of Yangtze River from July 2010 to July 2012. By using otolith as identification material, the age structure and growth characteristics of the specimens were studied, and the feeding habits of the specimens were analyzed by their intestinal inclusions. As a material for identification, the otolith was better than the others, and the success rate was 93.7%. The R. cylindricu population consisted of 7 age classes, mainly between 2-4 years old (79.89%). The relationships between body weight and length and between body length and otolith radius could be expressed as W=8×10^-6L^2.977 (r²=0.955, P<0.01) and L=8×10^-4R^2.149 (r²=0.945, P<0.01), respectively, and the Von Bertalanffy growth equation was L_t=389.37(1-e^{-0.177(t+0.739)}) and W_t=515.26(1-e^{-0.177(t+0.739)})^2.977. The age inflection point of body weight was estimated at 5.44 years. Diet habit analysis showed that R. cylindricus preyed all the year, with the main foods being algae, mollusks, and aquatic insects. In terms of numerical percentage, the majority of the foods were algae and mollusks (93.12%); in terms of weight percentage, the majorities were algae, mollusks and aquatic insects (78.38%). According to the results of this study, R. cylindricus was an omnivorous fish species. As compared with previous studies, the R. cylindricus had individually miniaturized, but its body weight changed little. Some suggestions for fishery resources protection were proposed to cope with the over exploitation of the R. cylindricus.

Key words: water-nitrogen interaction, microjet irrigation, water use efficiency, nitrogen use efficiency, gravel-mulched field.