Temperature stress affects growth, physiological function, and immune function in various fish species. The current research evaluated the potential effects of different water rearing temperatures; 10ºC (10.3 ± 0.05), 20ºC (20 ± 0.06), 30ºC (29.8 ± 0.08), and 35ºC (34.6 ± 0.05) for 6-weeks on growth, antioxidative, immune and gene expression profiles of bluegill sunfish (Lepomis macrochirus) . Sampling was performed at zero day, and the end of the third and sixth week . Growth performance (SGR and BMG) and condition factor were considerably influenced by variations in water temperature with the best performance for the 30ºC group and the lowest possible for the 10ºC group.
Temperature significantly affected the SOD, CAT and GPx activities with higher (P < 0.05) superoxide dismutase (SOD) in erythrocyte lysate in the 10ºC, 30ºC and 35ºC mostly pronounced at the 6th week . CAT activity showed most significant increase for 20ºC at 6 weeks (Fig. 1) . While GPx activity showed the most significant increase for 35ºC at day 0 and 6 wee ks and for 20 ºC at 3 weeks (Fig. 2).
The immune (lysozyme U/ml, and nitric oxide pmol /ml) parameters gave the highest increase in 20ºC groups at 6 weeks . The parameters values decreased and low (10ºC) and high (30 and 35ºC), with optimum values at intermediated temperature (20ºC ). The expression pattern of immune related gene α-2-macroglobulin (A2M) gene was higher for 20 and 30ºC groups and lower in 10ºC group. Also, heat Shock protein- 90 (HSP-90) was notably high for 20, 30, and 35ºC groups. .
Conclusively, our results demonstrated that temperature variations markedly alter growth antioxidants , and immune profiles; with the best performance at intermediate temperatures indicating the possible usage of tested parameters as indicators for temperature changes in aquaculture.