Abstract: The observation on the behaviors of Pelteobagrus vachelli fingerlings under varied water temperature and light intensities in a tank showed that the individual fingerlings had special selection between white and black substrates. At water temperature 30 ℃ and 20 ℃, the fingerlings swam more actively when the light intensity was lower than 15 lx, but the swimming activity reduced when the light intensity was higher than 15 lx. The duration the fingerlings stayed on white substrate decreased when the light intensity was less than 5 lx, and the decrement was larger at 30 ℃ than at 20 ℃. When the light intensity was higher than 5 lx, this duration tended to be less changeable. There were 4 types of schooling patterns, i.e., aggregating, scattering, resting, and group swimming. The formation of resting pattern was due to lower water temperature (7.0 ℃-9.0 ℃), while aggregating pattern was caused by high light intensity. The fish showed swimming in schooling under downy light intensity (1.2-209.0 lx), and the fish school dispersed when the light intensity was lower than 1.6 lx.

Key words: Fraxinus mandshurica, Root, Leaf, N availability, Biomass allocation