Food consumption and digestive enzyme activity of clarias batrachus exposed to various temperatures

The effect of temperature on the food consumption rate and the digestive enzyme activities of Clarias batrachus (80.60 +/- 5.34g) were evaluated. Fish were exposed to six different temperatures of 10, 15, 20, 25, 30 and 35 degrees C following an acclimation temperature of 25 degrees C. The rate of temperature change was 2 degrees Cday(-1). Highest food consumption was recorded at 25 degrees C. It gradually reduced with decreasing water temperature. Food consumption rate was significantly (P<0.05) lower at 10 degrees C compared with other treatments. Hence, 46.67, 8.20-23.58 and 1.02-6.15% reduced food consumptions were recorded in groups exposed at 10, 15 and 20 degrees C temperatures, respectively, compared with the 25 degrees C. The consumption rate was not affected in fish exposed at 30 and 35 degrees C. Total protease, trypsin and chymotrypsin activities were significantly (P<0.05) higher in fish exposed at 25 degrees C compared with others. Lipase activity was significantly (P<0.05) higher in fish exposed at 30 degrees C compared with others. Lowest enzyme activities were recorded at 10 degrees C. Water temperature below 25 degrees C affected the food consumption and digestive enzyme activities in fish that served as indicators of stress in fish.