The feeding experiment was conducted in 60-l tanks
arranged in a flow-through system, each treatment in
triplicate. Each tank was stocked with 15 rainbow trout
Oncorhynchus mykiss (average 126 g), which had been
grown previously on commercial pelleted feeds from
Nippon Formula Feed (Yokohama, Japan) during early
stages and Chubu Shiryo (Shizuoka, Japan) during
juvenile phase. The fish were offered the basal control
diet for a 2-week conditioning period. After this, they
were fed the control and three probiotic diets two times
daily to satiation for a period of 30 days, following
which the probiotic diets were withdrawn and the basal
diet was fed to the remaining fish in all treatments up to
45 days. The water temperature averaged 16F1 8C
throughout the experiment.