Abstract:Small-size fishes that have a short lifespan and high growth rate are important members of aquatic communities. Despite having relatively low commercial value, they often serve as forage fish for more commercially important species. Furthermore, small fish species are potentially key determinants of aquatic ecosystems. We evaluated the species composition, density, and biomass of small-size fishes in Niushan Lake, a typical shallow macrophytic lake along the middle reach of the Yangtze River. Based on macrophyte cover conditions, the lake was divided into three major habitat types: P. maackianus habitat (H2), and uncovered/ habitat (H3). Fish were sampled quantitatively in the three types of habitat using block nets that were placed seasonally between September 2002 and August 2003. We captured a total of 12 636 individuals comprising 27 fish species, among which 20 species were classified as small-size fishes. The tBased on an index of relative importance (IRI), Paracheilognathus imberbis, Toxabramis swinhonis, were the dominant small fish species, collectively accounting for 91.1% of the total catch. The Zippin’s removal method was used to estimate density and biomass of the eight dominant small-size fishes in each season and throughout the whole year. We observed seasonal variation in the calculated density and biomass. For the entire year, average total density and average total biomass of the eight dominant small-size fishes were 3.992 ind/(m2·year) and 6.073 g/(m2·year), respectively. Our results provide baseline information that is essential to the long-term monitoring of small-size fish communities in the shallow lakes in the Yangtze River basin. We suggest that targeted stocking of piscivorous fishes (Culter mongolicus) and optimization of the fish community structure may provide means to exploit and utilize