Thermal tolerance, growth and oxygen consumption of Labeo rohita fry (Hamilton, 1822) acclimated to four temperatures

Abstract

A 30 day feeding trial was conducted using a freshwater fish, Labeo rohita (rohu), to determine their thermal tolerance, oxygen consumption and optimum temperature for growth. Four hundred and sixteen L. rohita fry (10 days old, 0.38570.003 g) were equally distributed between four treatments (26, 31, 33 and 36 1C) each with four replicatesfor 30 days. Highest body weight gain and lowest feed conversion ratio (FCR) was recorded between 31 and 33 1C. The highest specific growth rate was recorded at 31 1C followed by 33 and 26 1C and the lowest was at 36 1C. Thermal tolerance and oxygen consumption studies were carried out after completion of growth study to determine tolerance level and metabolic activity at four different acclimation temperatures. Oxygen consumption rate increased significantly with increasing acclimation temperature. Preferred temperature decided from relationship between acclimation temperature and Q10 valueswere between 33 and 36 1C, which givesa better understanding of optimum temperature for growth of L. rohita. Critical thermal maxima (CTMax) and critical thermal minima (CTMin) were 42.3370.07, 44.8170.07, 45.3570.06, 45.6070.03 and 12.0070.08, 12.4670.04, 13.8070.10, 14.4370.06, respectively, and increased significantly with increasing acclimation temperatures (26, 31, 33 and 36 1C). Survival (%) wassimilar in all groupsindicating that temperature range of 26–36 1C isnot fatal to L. rohita fry. The optimum temperature range for growth was31– 33 1C and for Q10 valueswas33–36 1C. r 2005 Elsevier Ltd. All rights reserved.