Impacts of Different Exercise Routines on Rainbow Trout Rearing Performance

Exercising fish during hatchery rearing may provide considerable benefits. This study evaluated a combination of different exercise regimens and feeding levels during juvenile rainbow trout (Oncorhynchus mykiss) rearing for 109 days. Four treatments were used: 1. continual exercise at a water velocity of 12.2 cm s-1 and feeding to near-satiation (low exercise, low feed), 2. continual exercise at a water velocity of 30.5 cm s-1 and feeding an increased ration (high exercise, high feed), 3. exercise routine using a water velocity that alternated weekly between 12.2 cm s-1 and 30.5 cm s-1 and feeding to satiation (exercise routine, low feed), and 4. exercise routine and feeding an increased ration (exercise routine, high feed). Final tank weight, gain, percent gain,and feed conversion ratio were all significantly lower in the high exercise, high feed treatment compared to the other three treatments. Feed conversion ratio was significantly greater in the exercise routine, high feed treatment compared to both of the lower feed treatments. Specific growth rate and individual fish length and weight were all also significantly lower in the trout reared under constant high velocity compared to the other three treatments, but there was no significant difference in condition factor among treatments. Because the troutfed to satiation in this novel exercise routine grew similar to, and as efficiently as,the trout receiving low exercise and fed to satiation, this exercise regime can be used to obtain the benefits of exercise without sacrificing rearing performance.