Growth performance, physio-metabolic, and haemato-biochemical status of Labeo rohita (Hamilton, 1822) juveniles reared at varying salinity levels using inland saline groundwater

Abstract

A 120-day experiment was conducted to investigate the effect of different inland saline groundwater salinities on growth performance, nutrient utilization, physiological-metabolic responses, and haemato-biochemical indices of juvenile Labeo rohita. The experiment setup comprised 24 circular tanks, each of 400 L capacity with 250 L water volume, stocked with juvenile L. rohita (2.04 ± 0.01 g; n = 25). The experimental tanks were categorised as seven treatments with different salinity levels viz., T1 (2‰), T2 (4‰), T3 (6‰), T4 (8‰), T5 (10‰), T6 (12‰), and T7 (14‰) and one control (0‰) with triplicates. No significant difference (p > 0.05) in growth performance was observed with increasing salinity from control to T2, but the growth rate was found to be suppressed significantly (p < 0.05) from T3 to T7. The highest and the lowest survival was recorded in control (100%) and T7 (0%), respectively. Increasing salinity above T2 (4‰) significantly retarded growth and feed utilization in L. rohita. Fish reared up to T2 (4‰) showed the highest amylase and protease activity, but those reared in T3 to T7 displayed the decreasing trend of enzyme activities with an overall significant difference (p < 0.05). With increasing salinity, the activity of Aspartate aminotransferase activity (AST), Alanine aminotransferase activity (ALT), Superoxide dismutase (SOD) and Catalase activity (CAT) in the liver of L. rohita were increased significantly (p < 0.05). Na+/K+-ATPase activity of gill significantly (p < 0.05) declined with increasing salinity. Similarly, total serum protein, albumin, globulin, Albumin:Globulin ratio, Ht%, haemoglobin and total erythrocyte count were reduced significantly (p < 0.05) with increasing salinity. In contrast, total leucocyte count was found to be significantly increased with increasing salinity. Serum biochemical response and stress indices (serum cortisol and serum glucose) were remarkably affected by salinity and differed significantly (p < 0.05) among treatments. The present study suggests that salinity level in the range of 0–4‰ is ideal for the culture of L. rohita in inland saline areas without affecting the overall fish performance. Further, it is also concluded from the study that survival of 72 to 88% could be obtained in inland saline groundwater having salinity up to 12‰, which suggests that degraded inland saline areas can be successfully utilized for sustainable aquaculture.