Alterations of serum electrolytes and biochemical indices of Panagasianodon gigas subjected to different water temperatures and the appropriate temperature range for sustaining life

ABSTRACT The effects of cold and heat shocks on serum electrolyte and biochemical changes in Panagasianodon gigas. Cold shock was conducted as follows: 25–22°C, 25–19°C and 25–13°C; and heat shock: 25–28°C, 25–31°C and 25–37°C. The lowest Na+ was found in the group exposed to 25–13°C and 25–37°C, while the highest Na+ was observed in the 25–31°C group. The K+ significantly increased with decreases in water temperature. The Cl- was significantly decreased and increased when decreasing and increasing water temperature, respectively. The serum CO2 level was affected by cold shock but was not affected by heat shock. The highest and lowest Na+/K+ ratio was found in the group exposed to 25°C–31°C and 25°C–13°C, respectively. Moreover, the Na+/Cl- ratio showed a similar trend to that of the Na+/K+ ratio. Furthermore, the highest (Na+ + K+)/Cl- ratio was found in 25–31°C group. The highest glucose was found in all the cold shock groups. Albumin, globulin, total protein, triglyceride and cholesterol levels were significantly decreased after exposure to cold and heat shocks. These results demonstrated that 25–28°C is the appropriate temperature range for this species whilst other ranges influenced biochemical and physiological indices.