Influence of increased photoperiods on growth, feed comsumption and survival of juvenile mirror carp (Cyprinus carpio linnaeus,1758)

A growth trial was conducted in order to determine the effects of increased photoperiod regimes on growth performance, feed intake and survival of mirror carp (Cyprinus carpio Linnaeus, 1758) in laboratory conditions for 90 days. Triplicate groups of fish (6 g mean body weight) were exposed to photoperiod regimes of 12 hours light:12 hours dark (12L:12D), increased photoperiods of 16 hours light:8 hours dark (16L:8D) and continuous light (24L:0D), respectively. At the end of the trial, growth was highest in the group subjected to continuous photoperiod, and appeared significantly different (p<0.05) than the rates recorded in the other photoperiod regimes. Under the continuous (24L:0D) photoperiod, feed conversion ratio (FCR) was significantly (p<0.05) better than those in the other photoperiod treatments. No significant difference (p>0.05) was found in the FCRs between the 12L:12D and 16L:8D groups. Feed intake was not significantly (p>0.05) affected by photoperiod treatments. No mortality was observed in the continuous (24L:0D) photoperiod group, however, a mortality of about 3 % was recorded in the other two groups. For a better growth and lower food conversion rate, a continuous (24L:0D) photoperiod exposure is suggested best for rearing of juvenile carp.