Effect of Water Temperature on Feeding Rhythm in Common Carp (Cyprinus carpio haematopterus Temminck et Schlegel)

Feeding rhythm of common carp was investigated from 4℃ to 34℃. The results indicated that there was a diel feeding rhythm for both adult (630-850 g) and youth (61-91 g) at all tested temperatures. There were two main activity peaks at 8:00-11:00 a.m. and 19:00-23:00 p.m., during which feeding quantities were 10.68%-32.53% and 16.25%-33.41% of the daily intake, respectively. When water temperature dropped to below 10℃, the feeding peak concentrated at 8:00-11:00 a.m. and 19:00 p.m. to 4:00 a.m. At 6℃, though both adult and youth would still feed, the feeding quantities were only 0.01% and 0.35% of body mass. Daily feeding rate of adult and youth reached 1.21% and 2.63% at 14℃, respectively. Both adult and youth carps reached the maximum daily feeding rate at 28℃, being 2.84% and 12.06% of body mass, respectively. The daily feeding rate of adult and youth reduced suddenly after at 34℃, and the daily feeding rate was only 0.74% and 9.45% of body mass, respectively. There was significant difference in daily feeding rate at different water temperatures (P<0.05).