Effects of water temperature, photoperiod and light intensity on survival, feeding and growth of Schizothorax biddulphi juveniles and their tolerance of salinity and alkalinity

In this paper, we investigated the effects of water temperature, photoperiod and light intensity on the survival, feeding and growth of Schizothorax biddulphi juveniles by using experimental ecological methods; predicted the optimal growth conditions for the juveniles by Box-Benhnken design; and studied the saline alkali tolerance of juveniles by single factor static toxicity acute test. The results show that the survival rate of the juveniles was above 85% at 5−25 ℃. The feeding rate, length growth rate and specific growth rate reached the maximum values at 20 ℃. When the photoperiod was 16 L∶8 D and the light intensity was 500 lx, all the indices of the juveniles reached the maximum values. Under conditions of water temperature of 12.98 ℃, daily light time of 15.07 h and light intensity of 670.27 lx, the best survival, feeding and growth were obtained. The LC₅₀ of NaCl salinity was 4.01, 3.62, 3.29 and 2.92 g·L⁻¹ at 24, 48, 72 and 96 h, respectively, and the safety concentration (SC) was 0.89 g·L⁻¹. The LC₅₀ of NaHCO₃ alkalinity was 97.14, 86.75, 80.26 and 74.52 mmol·L⁻¹ at 24, 48, 72 and 96 h, respectively, and the SC was 20.75 mmol·L⁻¹.