Research on salinity tolerance of Sinogastromyzon szechuanensis

We measured the salinity tolerance of Sinogastromyzon szechuanensis with average body mass of (8.495±1.11) g, to provide theoretical basis for its conservation and artificial culture. The results show that the half lethal concentrations (LC₅₀) of salinity at 24^th, 48^th, 72^nd and 96^th hour was 10.50, 10.15, 9.83 and 9.46 g·L⁻¹, respectively. The safe concentration was 2.32 g·L⁻¹. After 4 h of salinity stress in S. szechuanensis, compared with the initial stage, the respiration frequency in groups with salinities less than 7 g·L⁻¹ decreased, and the respiration frequency of groups with salinity higher than 7 g·L⁻¹ increased significantly (P<0.05). The respiratory rate of 2 g·L⁻¹ group was (150.0±5.57) times·min⁻¹, significantly higher than that of the 0 g·L⁻¹ group (P<0.05). Being adapted to (0–7) g·L⁻¹ salinity stress for 4 h, the asphyxia point of S. szechuanensis in 2 g·L⁻¹ group was the lowest [(0.81±0.02) mg·L⁻¹]. After 96 h adaptation, the asphyxia point of S. szechuanensis in each salinity group decreased, and the asphyxia point of (0–1) g·L⁻¹ was the lowest [(0.60±0.06) mg·L⁻¹]. It is concluded that S. szechuanensis has low salinity tolerance, and its asphyxiation point is higher than that of common freshwater fish. The critical value of using salinity to monitor the salinity to the safe concentration of S. szechuanensis is (150.0±5.57) times·min⁻¹. Therefore, the salinity should to be conctrolled as (0–1) g·L⁻¹ in transportation, which is helpful to enhance the hypoxia tolerance and survival rate of S. szechuanensis.