Integrative analysis of growth, physiology, and tissue responses in Labeo catla spawns under low-salinity conditions

In the scenario of climate change induced freshwater salinization, low-salinity aquaculture is an operational strategy to sustain aquaculture production in vulnerable areas across the globe. The present work attempts to assess the effects of low-salinity environment on growth, survival, histological changes, and biochemical responses of Labeo catla during its early life stages. Salinity exposure experiments were conducted for a duration of twenty days. Four treatments were assigned with salinity 0 g L⁻¹ as control, 2.5 g L⁻¹ as T1, 5 g L⁻¹ as T2, and 7.5 g L⁻¹ as T3. Growth performance and survival rate significantly (p < 0.05) differed across all experimental groups, and 100% mortality occurred in T3. The salinity concentration had a substantial impact on biochemical indices of whole-body homogenate of the catla spawns. The biomarkers cortisol, total protein, glucose, catalase, and superoxide dismutase varied significantly (p < 0.05) between the treatment groups. The histology of gills exposed to varying salinity reveals histoarchitectural differences. The hyperplasia in chloride cells was observed at elevated salinity concentrations, suggesting acclimatizing changes to hyperosmotic changes. With a survival rate more than the national average, and positive attributes from integrated biomarker response analyses, low-salinity condition at 2.5 g L⁻¹ is suggestive of developing successful strategy for culture of L. catla spawns in affected areas due to salinity intrusion.