Diet of the zooplanktivorous icefish Neosalanx pseudotaihuensis Zhang

Abstract

The icefish Neosalanx pseudotaihuensis (Salangidae) is a small transparent fish with a life cycle of about one year. This fish species is increasingly introduced to waterbodies in China in order to enhance fish production. Diet of the icefish was investigated from the 1996 cohort (June 1996–April 1997) in Xujiahe Reservoir (central China). The gut content analysis of 1001 specimens (size range: 21–72 mm in total length) revealed that the major components of the icefish diet were Leptodora kindti, Daphnia galeata, Diaphanosoma dubia, calanoids and cyclopoids. L. kindti and D. dubia were strongly selected for by the fish. However, the icefish did not show strong positive selection for Daphnia galeata, although it was a very important contributor to fish diet. Bosmina spp. were always negatively selected for by the icefish. The larger-sized fish showed a stronger preference for copepods, suggesting improved capture efficiency for evasive prey with increasing fish size.