The effects of combined salinity and temperature on growth survival and selected physiological parameters of striped snakehead (Channas striata)

Abstract

Striped snakehead, Channa striata (Bloch, 1793) is one of the most popular freshwater culture species in Mekong delta, Vietnam. This study aimed to find the effects of combined temperature and salinity on growth, survival and selected physiological parameters of this species. The experiment was set up in 500-L composite tanks containing 200-L water. The experiment was conducted using completely randomized design with 3 replicates including three elevated temperatures (270C, 300C and 330C) in combination with 3 salinities (0‰, 5‰ and 10‰). Each tank was stocked 300 individuals. Striped snakehead at hatching stage were used for this study. Salinity and temperature of the water in the treatments were increased by 2‰ and 2oC per day, respectively. The experiment was lasted for 90 days. The body mass of fish was monitored at 30, 60 and 90 days for calculating the growth and survival rate. Blood was collected at 90 days to measure hematocrit, hemoglobin, red blood cells, white blood cells, osmotic pressure, [Na+] and [Cl-]. The results showed that the interaction of temperature and salinity did not affect growth and survival rate. The salinity affected both growth and survival rate, where the highest weight gain and survival rate in treatment 270C combined with 5‰ (7.53±0.12 g) and 300C combined with 0‰ (7.884.71 g), respectively. The plasma osmolality was changed, but the number of red blood cells, white blood cells, hematocrit, hemoglobin, [Na+], [Cl-] were not changed. The plasma osmolality was highest (40971.8 mOsm/kg) in treatment 300C combined with 5‰ and the lowest (2835.72 mOsm/kg) was in treatment 330C combined with 0‰. In conclusion, hemoglobin, hematocrit and number of blood cells decreased at elevated temperature and high salinity. Ion [Na+] and [Cl+] levels increased with the increased of salinity.