Juvenile unsexed crucian carp, approximately 5 months old
(8.78 ± 0.71 cm, 14.4 ± 1.36 g), were obtained from the Nanjing
Institute of Fishery Sciences (Nanjing, China). All fish were acclimatized
in dechlorinated municipal water for two weeks prior to the
experiments, and their mortality was below 1%. The fish were fed
every day with midge larvae (Chironomus sp.) (6% of body weight/-
day). Feces and uneaten food were removed every day by suction.
The fish were not fed for 24 h prior to the experiments, and no food
was provided during the test period. Animal care and experimental
protocols were performed in accordance with the standard procedures
of the Institutional Animal Care and Use Committee