Effects of photoperiod on fish growth and Feeding in the rainbow trout (Onchorynchus mykiss) Juvenile

Light is one the important and effective environment factor in fish life. The fish isexposed to long photoperiod than short photoperiod cycles may provide higherenergy conservation. The aim of this study was to evaluate the effect of differentphotoperiods on the growth rate, feed conversion rate of young rainbow trout. In thisresearch, effects of photoperiod were studied on growth and some feeding parametersin 4 photoperiod treatments (Light/Dark hour) (12L:12D control group; 24L:0Dcontinuous light group; 18L:6D extended light group and 6L:18D short light group)for 6 weeks. Fish exposed to 24L:0D (continuous light group) had a significantlyhigher growth rate followed by 18L:6D, 12L:12D and 6L:18D photoperiods(P<0.05). The feed intake increased with extended of duration of light regime andsignificant differences (P<0.05) were found among groups. Juvenile rainbow troutsubjected to the long light periods (24 and 18 h) had significantly better growth andfeed utilization efficiency than those exposed to intermediate or short light periods(12 or 6 h).

Keywords:

Photoperiod , Growth , Feeding , Onchorynchus mykiss