Comparison of some growth parameters of rainbow trout (Oncorhynchus mykiss) farming in a new design of ellipsoid ponds with circular flow (Foster- Locus) and raceways

Intensive culture of  rainbow trout is usually conducted in a variety of culture systems. The objective of this study, was to compare the performance of fish growth and welfare in a new design of elliptic ponds with circular flow; Foster-locas ponds (FLPs) and raceway ponds (RPs) under field conditions. The experiment was designed in two treatments with three repeats. For this purpose, three FLPs and three RPs were constructed. Each pond was randomly stocked by rainbow trout fish with initial average weight of approximately 40±5 g. Stocking density was 120 fish/m3 during study. Fish fed commercial diet (Chineh Company). Feeding operation conducted according to the manual by consideration of water temperature and fish weight at amount of 1.3 percent of biomass. Based on results, the fish survival rate in FLPs and RPs were  high (98.05% and 97.39% respectively). No significant difference in growth parameters were observed between RPs and FLPs, but fish growth rate in FLP was higher than RP (P> 0.05). Mean water quality factors (dissolved oxygen and PH) were favorite in FLP for culture of  rainbow trout and don,t have significant difference with those in RP (P> 0.05). The results confirmed when water quality is maintained in safe level ranges, FLPs can be used as a substitute of RP for intense rainbow trout culture.