Abstract: This paper studied the spatial distribution of small fishes in a shallow macrophytic lake, Niushan Lake in spring 2003, and its relations with habitat heterogeneity. Based on the macrophyte cover condition, distance from lake shore and water depth, two representative habitat types in the lake were selected. Habitat A was near the shore with dense submersed macrophyte, while habitat B was far from the shore with sparse submersed macrophyte. Small fishes were sampled quantitatively by block net (180 m²), and their densities within the net area were estimated by multiple mark-recapture or Zippin’s removal method. The results showed that there were some differences in species composition, biodiversity measurement, and estimated density of small fishes between the two habitats: 1) the catches in habitat A consisted of 14 small fish species from 5 families, among which, benthopelagic species Rhodeus ocellatus, Paracheilognathus imberbis and Pseudorasbora parva were considered as dominant species, while those in habitat B consisted of 9 small fish species from 3 families, among which, bottom species Rhinogobius giurinus and Micropercops swinhonis were dominant; 2) the Bray-Curtis index between the two small fish communities was 0.222, reflecting their low structure similarity, and no significant difference was observed between their rank/abundance distributions, both of which belonged to log series distribution; 3) the total density of 9major species in habitat A was 8.71 ind·m^-2, while that of 5 major species in habitat B was only 3.54 ind·m^-2. The fact that the spatial distribution of the small fishes differed with habitats might be related to their habitat needs for escaping predators, feeding, and breeding, and thus, aquatic macrophyte habitat should be of significance in the rational exploitation of small fish resources as well as the conservation of fish resource diversity.

Key words: Intersubspecific crosses of rice (Oryza sativa), Panicle traits, Genotype譭nvironment interaction, Additive譇dditive epistasis, Heritability