Interrelationship of Photoperiod with Growth Performance and Feeding of Seawater Farmed Rainbow Trout, (Oncorhynchus mykiss)

Abstract

Juvenile of rainbow trout (Oncorhynchus mykiss, weight 27.39 +/- 0.16 g) were reared under four photoperiods (Light/Dark hour) (11L:13D control group; 24L:0D continuous light group; 18L:6D extended light group and 6L:18D short light group) to examine their growth performance and some feeding parameters in sea water conditions. Fish were fed on a commercial diet until satiation for 8 weeks of the trial. Fish exposed to 24L:OD (continuous light group) had a significantly higher daily growth rate, relative growth rate and specific growth rates followed by 18L:6D, 1 1L:13D and 6L:18D photoperiods (P<0.05). The results demonstrated that the growth performance and feed utilization of rainbow trout can be stimulated clearly by using a continuous (24L:0D) or extended light (18L:6D) photoperiods in sea water.