Effects of acclimation temperature regime on the thermal tolerance, growth performance and gene expression of a cold-water fish, Schizothorax prenanti.

Acclimation temperature is crucial for the optimization of a condition in aquaculture; we experimentally investigated the effects of temperature acclimation on the thermal tolerance, growth performance and gene expression levels of heat shock proteins (hsp70), growth hormone (gh) and insulin-like growth factors (igf-1) in Schizothorax prenanti, a cold-water fish in the Yangtze River basin. Critical thermal maximum (CT), critical thermal minimum (CT), lethal thermal maximum (LT), lethal thermal minimum (LT), feeding intake (FI), feeding efficiency (FE), and specific growth rate (SGR) were assessed at three stable temperatures (17, 22 and 27 °C) and one variable temperature (22 ± 5 °C) for 28 d. Better growth performance was observed under variable treatment compared to stable treatments. However, fish under the 27 °C treatment exhibited much weaker growth performance than those in the 17 °C treatment. Fish under variation temperature treatment fed like those under 22 °C treatment; the fish exhibited similar SGR but a higher gh and hsp70 level under variation temperature treatment. This may be due in part to a trade-off energy expenditure to deal with the temperature fluctuation. Together, these findings suggest that juvenile Schizothorax prenanti are resilient to daily fluctuations within the temperature tested here.