Feeding Habits of Hemibagrus pluriradiatus (Vaillant) in Yuanjiang River
元江越鳠的食性研究

This paper deals with the food composition, feeding intensity and feeding morphology of Hemibagrus pluriradiatus (Vaillant). 251 individuals, with body-length ranging from 109 mm to 295 mm and body-weight ranging from 14.6 g to 273.5 g, caught by electric shock from Yuanjiang River in Yunnan Province, China, from June 2008 to May 2009, were analyzed. The results showed that H. pluriradiatus is a euryphagous fish feeding on a wide range of food items including small fish (mainly loaches), aquatic insect larvae (mainly Cybister), aquatic and terrestrial insects, mollusc, annelida, crustacean, fish eggs, frogs, rotifers, cladoceran, copepoda, cereals, macrophytes, algae and etc. Small fish had an average occurrence rate of 64.2% and accounted for 46.90% in weight in the stomach content. Aquatic insect larvae had an average occurrence rate of 73.8% and accounted for 40.00% in weight together with insect imago. This indicated that small fish and aquatic insect larvae were the most important food items for H. pluriradiatus. H. pluriradiatus is also a guttler. Its stomach fillness index can reach 11.6%~16.2% at satiation. As the body-length increase, its food composition simplified and feeding intensity decreased, the occurrence rate of aquatic insect larvae decreased and of imago increased. Terrestrial insects appeared in the stomach of individuals with body-length over 160 mm. The seasonal variation of food composition was obvious while that of feeding intensities was less obvious. In conclusion, H. pluriradiatus though it takes in more animal food, is a bottom feeder omnivore.