Abstract: In this paper, the dynamic variations of the fish community as well as the dominance, diversity index, and community structure of main fish species in the Lishui section (28°16′47.03″N-28°24′42.66″N, 119°42′31.41″E-119°57′13.03″E) of Oujiang River main stream were analyzed, based on the fish resources survey in March (spring), June (summer), September (autumn), and December (winter), 2009. There were 47 species of fishes, belonging to 5 orders, 12 families and 34 genera. Comparing with that in 1972, the fish species number in 2009 was decreased by 28.8%. A total of 8 dominant species, i.e., Distpechodon tumirostris, Sinibrama macrop, Pelteobagrus fulvidraco, Hemobarbus labeo, Leiocassis taeniatus, Pelteobagrus vachelli, Acrossocheilus wenchowensis, and Cyprinus carpio were detected, of which, D. tumirostris and S. macrops were dominant across 4 seasons, and the others were only dominant in one of 4 seasons. The dominance of the fish community varied from 0.578 to 0.747, being the highest in winter. The variation range of Margalef index (D), Shannon index (H), and Pielou index (J) was 2-4, 1-2, and 0.3-0.6, respectively, suggesting that the diversity and abundance of the fish community were at normal level. The seasonal turnover index and migration index showed that the fish community had obvious seasonal change, and the Jaccard index and Sorenson index indicated that the similarity of the fish community in 3 habitats was moderately dissimilar.

Key words: Community structure, Height class, Diameter class, Dynamic analysis