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°cC to 34°C. 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°C, the feeding peak concentrated at 8:00–11:00 a.m. and 19:00 p.m. to 4:00 a.m. At 6°C, 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°C, respectively. Both adult and youth carps reached the maximum daily feeding rate at 28°C, being 2.84% and 12.06% of body mass, respectively. The daily feeding rate of adult and youth reduced suddenly after at 34°C, 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).