Role of temperature changes in embryo development of rainbow trout (Oncorhynchus mykiss), and larvae and fingerlings growth indices

Temperature plays an important role in physiological processes in animals. In aquatic animals, the role of temperature in embryonic development has been proved and investigation and recognition of these changes in the production of larvae and quality of fish is of great importance in the economic production dimension. In this study, the effect of water temperature changes on hatching rate and survival of rainbow trout embryo, larvae and fingerlings were investigated. The experimental treatments included of waterborne temperature 10 (control treatment), 12 (treatment 1) and 14 (treatment 2) °C in three replicates. The mean percentage of hatching in treatments 1 (85.04±0.78) and treatment 2 (84.71±1.07) were significantly higher than control treatment. (82.90±0.97) (P<0.05). The mean percentage of larvae survival in experimental treatments showed a significant increase in treatments 1 (88.24±0.78) and 2 (91.10±1.57) compared to control (80.30±1.09) (P<0.05). Also, the lowest survival rate was observed in 14°C treatment, so it can be concluded that with increasing temperature, fish metabolic rate increases and at 12°C, the survival conditions of larva and fingerlings are better, in treatment 2, this rate was significantly higher than treatment 1 (P<0.05). In the later stages of growth, it was found that the survival rate of salmon fish decreased with increasing temperature compared to the control, so that the lowest survival rate was observed in 14 °C treatment.