Salinity-induced variations in growth performance, stress biomarkers and biochemical profiles of striped catfish (Pangasianodon hypophthalmus, Sauvage, 1878).

Environmental salinity affects the growth, survival rate and physiological functions of fish. In this study, the effects of salinity stress on Pangasianodon hypophthalmus (Sauvage, 1878) fingerlings were examined over a 90-day period. After acclimatization, a total of 300 P. hypophthalmus fingerlings were randomly assigned into three replicates and divided into five treatment groups with salinity levels of 0‰, 6‰, 12‰, 18‰, and 24‰ and with a stocking density of 20 fish per aquarium. After 90 days, the final weight, weight gain, weight gain percentage and specific growth rate significantly (p < 0.0001) decreased with increasing salinity, while feed conversion ratio values increased. The viscerosomatic index and hepatosomatic index significantly (p < 0.0001) increased up to 12‰ salinity, then decreased. Survival rate differed significantly (p < 0.0001), with a maximum at 12‰ and a minimum at 24‰ salinity level. Moisture and ash content were significantly higher (p < 0.0001) at 18‰ and 24‰. Crude lipid and protein contents were significantly higher (p < 0.0001) at lower salinity levels. Haematological content was significantly higher (p < 0.0001) at 0‰, 6‰ and 12‰ salinity levels, then decreased. The values of globulin, albumin and total protein also declined significantly (p < 0.0001) with increasing salinity. Conversely, values of alanine aminotransferase and aspartate aminotransferase increased significantly (p < 0.0001) from 0‰ to 24‰. Total cholesterol, total glyceride and high-density lipoprotein cholesterol were significantly higher (p < 0.0001) at 12‰ and lower at 24‰. Stress parameters, such as glucose and cortisol, and lipid peroxidation parameters, such as catalase, glutathione peroxidase, superoxide dismutase and malondialdehyde, increased significantly (p < 0.0001) as the salinity level increased. This study demonstrates that the optimal salinity level for the cultivation of P. hypophthalmus in inland saline groundwater is 12‰, which ensures the maximum survival rate.