Effects of Thermal Shock on Some Freshwater Fishes

In order to understand the stress encountered by freshwater fish as a result of thermal discharges into waters, we undertake thermal shock experiments study. The TL₅₀ values of four freshwater fishes increased with increasing acclimation temperature. The UILT values for silver carp, bighead carp, grass carp and common carp were 37.1degC, 35.6degC, 37.7degC, 37.3degC, respectively. The results obtained showed similar type of heat acclimation for CTMax and LRR. Data of CTMax, LRR and TL₅₀ indicate the importance of acclimation temperature relative to their upper thermal tolerance limits of fishes. In fish acclimated at 30degC , acute estimated final thermal optimum temperature was 29.9degC(silver carp), 31.2degC(bighead carp), 30.3degC (grass carp) and 30.1degC (common carp), respectively. The preferred temperature range of silver carp, bighead carp, grass carp, common carp was 28.0-32.0degC, 28.0-33.0degC, 27.0-34.0degC, 27.4-31.21degC.