Impacts of thermal treatments on growth performance, blood factors, biochemical parameters, and immunity of juvenile kutum (Rutilus kutum) from the Caspian Sea

Considering the decisive role of water temperature in the growth and immunity of farmed aquatic species, the effects of different temperature treatments on the growth and immunity of Rutilus kutum were investigated in the present study to achieve optimal values in line with research efforts to study the rearing biology of the species. Relationships between optimum growth and survival temperatures with hematological, biochemical, and immunological parameters in R. kutum from the Caspian Sea were investigated in an experiment with a completely randomized design with six treatments (17, 20, 23, 26, 29, and 32 °C) in three replicates each with 20 fish (2.55 ± 0.05 g) for 60 days. Treatments of 23 and 26 °C had significant effects on growth performance compared to the other treatments (p < 0.05) and the highest survival rate was recorded at 17 °C (p < 0.05). Red blood cells (RBC), hemoglobin, and hematocrit percentages at 29 °C were higher than the other treatments (p < 0.05). White blood cell (WBC) count and lymphocyte percentage were greater at 29 and 23 °C than the other treatments, respectively (p < 0.05). The highest amounts of total protein, albumin, and globulin at 23 °C were different from those at 29 °C and 23 °C (p < 0.05). The fish at 29 and 32 °C had higher levels of glucose than the other treatments (p < 0.05). In immunity parameters, maximum and minimum levels of lysozyme and the complement were observed in treatments at 17 and 32 °C, respectively (p < 0.05). Treatments of 23-26 °C were the optimal temperature range for the growth and survival of R. kutum, which could play an important role in improving growth performance, blood characteristics, and the immunity of this valuable species.