Setipinna taty,is a commercially important fish distributed from the northern East China Sea to the Bohai Sea,and plays an important role in the marine ecosystems.In recent years,the catches were mainly composed of juveniles,and characterized by lower age population structure.In the present paper,the diet composition and ontogenetic variation in the feeding habits of Setipinna taty at fork length(FL)of 35-79 mm were examined by applying the KruskalWallis test,a chisquared test and the cluster analysis,according to the total of 207 samples from seasonal bottom trawl surveys in the central part of Yellow Sea in August 2008.Based on stomach contents analysis,the Setipinna taty was a generalist and more than 40 prey species were ingested.Crustaceans,including copepodas and euphausiaceas,were the most important prey groups,accounting for 94.65% of the total food by numerical percentage.At the species level,Paracalanus parvus, Calanus sinicus, Labidocera euchaeta and Euphausia pacifica were the most important prey.The relative importance of polychaetas,gastropodas and bivalvias was comparatively low.The feeding intensity,as indicated by the percentage of empty stomach(PES)and mean stomach fullness index(MSFI),varied significantly among different classes of sizes.The MSFI increased with increasing fish size,but the PES did not present the obvious trend of change.The percentage of euphausiaceas and mysidaceas increased significantly with increasing fish size,whereas the percentage of copepodas decreased.The Levin’s standardized indexes of each group are all below 0.6,which indicated that Setipinna taty has narrow dietary breadth.And the Levin’s standardized index is less and less with the increasing of fish size,and this shows that the fish’s diet becomes more and more especial.So they can make full use of environmental resources and enhance their ability to accommodate the impact of environmental fluctuation.The mean weight of prey,besides,also becomes larger and larger with the increasing of fish size.Cluster analysis revealed that there was an abrupt change in diet composition in the fish at about 45 mm FL.Copepodas dominated the diet of fish smaller than 45 mm FL,whereas euphausiaceas and mysidaceas were the dominant prey for fish greater than 45 mm FL.The result shows that the ontogenetic variation of Setipinna taty is not related with the age,but with the length.