The phosphorus release from trout feces and feed at the low water temperatures (8 degrees C) occurred slowly, while at high water temperatures (20 degrees C) on the second day reached maximum levels (4.45 and 4.12 mg L-1 respectively), and then decreased to the lower level at the end of day 11 (1.43 and 0.96 mg L-1 respectively). The total released nitrogen concentration was increased gradually in both fish feces and feed day by day. Total nitrogen level was reached to the highest concentration at day 11. Additionally, there was an obvious nitroaen release detected by water temperature increments (p<0.05), i.e. higher water temperatures promoted and caused higher nitroaen emissions.