Assessing Growth, Survival, and Physiological Responses of Gangetic Mystus ( <i>Mystus cavasius</i> ) to Incremental Salinity Levels: Implications for Aquaculture Management in a Changing Climate

Climate change is causing saline intrusion, negatively affecting aquaculture productivity on a global scale. It is necessary to explore suitable species for coastal aquaculture in water with low to moderate salinity. Thus, the objective of the present study was to assess the impact of salinity on the growth performance, muscle composition, and blood parameters of a farmed fish, Gangetic mystus ( Mystus cavasius ). For this experiment, the fingerlings were raised in the aquarium for 60 days. Three distinct salinities, specifically 3, 6, and 9 parts per thousand (ppt), were employed for treatment 2 (T2), treatment 3 (T3), and treatment 4 (T4), whereas treatment 1 (T1) was referred to as the control with a salinity of 0 ppt. Increasing salinity did not have any influence on the water quality parameters. The survival rates were 97.5 ± 0%, 96.25 ± 1.25%, 92.5 ± 2.5%, and 90 ± 5% for T1, T2, T3, and T4, respectively. The highest specific growth rate (SGR) and the percentage of weight gain (PWG) and the lowest food conversion ratio (FCR) were recorded at T1. T2 and T3 showed descending values for SGR and PWG and ascending values for FCR. Moreover, the body protein percentage reduced by about 2%, and lipids increased by 13% in T3 compared to T1. RBC and Hb exhibited an inverse relation with increasing salinity, whereas WBC and glucose displayed an opposite trend due to stressed conditions. Thus, the study implies that while salinity does hinder growth performance and compromise the immune system to some degree, M. cavasius is capable of enduring salinity levels of up to 6 ppt while maintaining a satisfactory survival rate.