عنوان مقاله [English]
The most basic needs of fish breeders is the enhancing the immune system and increasing growth and survival of fishes in their early life stages. Therefore, an experiment was designed to determine the effect of mineral supplementary on the survival of fishes and some safety variables were investigated on rainbow trout fish (Oncorhynchs mykiss) at a fish farm located in Amol. This supplementary included 8 mineral materials the zinc, copper, cobalt, manganese, magnesium, selenium and iron. Six diets containing different amounts of mineral premixes with 2, 3 and 4% of the minerals of treatment 1 were designed. Seven hundred young fishes with initial weight 40 ± 1 g were divided into 6 treatments and 3 replications and 40 young fishes were randomly assigned to any place. Young fishes were fed the diets for 12 weeks. In all experiments, control treatment has the lowest level of the safety variable of fish. The results showed that the survival rate of young fishes in all treatments was 100% and no deformity, such as changing the gill cover, unusual swimming with horizontal and vertical curvature of the spine of rainbow trout fishes was observed during the 12 week period of culture. Also, the significant differences were observed between total protein, hematocrit, white blood cells, red blood cells and albumin (P≤0.05). Some parameters of hematology of fishes were analyzed in twice sampling. It was not observed significant differences between two times of sampling, but in treatments in the differential count of white and red blood cells were observed the significant differences (P≤0.05). Furthermore, more safety level related to treatments 1 and U. The results showed that the amount of minerals to improve safety indices of rainbow trout young fishes compared to the diet recommended U is one percent more.