The comparison of growth parameters of Iranian and imported Spanish strains of rainbow trout (Oncorhynchus mykiss) reared in two water sources of river and spring

Annually, millions of rainbow trout frys are produced in Iranian hatcheries, however, millions of selected stocks of rainbow trout eyed eggs are also imported for breeding in farms. Despite the interest of many rainbow trout farmers to use imported fish for breeding, there is no clear information about the superiority of growth and survival of these imported strains over the rainbow trout that are produced in Iranian hatcheries. For this purpose, in the present study, the growth parameters of 432 individuals of either imported Spanish and Iranian strains of rainbow trout reared in 12 ponds using both river and spring water sources (four treatments and three replicates) were investigated and compared for 90 days. At the end of the experiment, a significantly higher weight and length gain, and specific growth rate was observed in Spanish rainbow trout compared to Iranian strain in both water sources (river and spring) (p < 0.05). Moreover, the food conversion factor was significantly lower in Spanish strain than Iranian rainbow trout) (p < 0.05). These results showed that the selection breeding could remarkably enhance growth performance and consequently cause more production and profit for rainbow trout farmers.