Short‐term exposure to higher temperature triggers the metabolic enzyme activities and growth of fish Labeo rohita fed with high‐protein diet

Six hundred Labeo rohita (average weight, 6.78g) were distributed in 24 tanks (25 fish per tank), which were allotted to eight experimental groups in triplicates. Half of the experimental groups were maintained at ambient water temperature of 26 degrees C, whereas the other half were exposed to 32 degrees C for 1week then later maintained at 26 degrees C for 4weeks. Fish reared under different temperature regimes were fed one of the four diets containing 200gkg1, 300gkg1, 400gkg1 or 450gkg1 protein. Growth, feed efficiency and protein retention were higher at 32 degrees C and continued for the next 2weeks after decreasing the temperature. The dietary protein level and water temperature interactions were more effective in modulating the response of hepatic glucokinase than that of hexokinase and pyruvate kinase. In contrast, hepatic gluconeogenesis was not affected by rearing temperature. Hepatic aspartate aminotransferase and alanine aminotransferase activity was found higher (P<0.05) at low temperature and at high protein level. It is suggested that the metabolic activities of fish are triggered by short-term exposure to higher temperature and the increased metabolic activity extended for a duration of 3weeks during which 400gkg1 dietary protein level was found to support growth of fish.