Influence of supplemented diet with Pediococcus acidilactici on non-specific immunity and stress indicators in green terror (Aequidens rivulatus) during hypoxia

Green terror fish were fed for two months with three types of feed including: control diet (C), diet containing 2% fish oil (O) and diet containing fish oil supplemented with 0.1% Pediococcus acidilactici bacteria (PA). At the end of the feeding period, 50 fish of different groups (n = 3) with an average weight of 4.28 g were transferred to 9 tank. Hypoxia tests were set out by sampling at three times including before hypoxia (BH) initiation, hypoxia stress spot (H) and starting mortality (SM). In fish submitted to the diet containing P. acidilactici bacteria, the immune indices of lysozyme activity (4.08, 4.19 and 4.85 μg/ml)], complement activity (2.65, 2.77 and 2.1 U/ml) and total immunoglobulin (10.05, 10.25 and 9.9 μg/ml) improved in all stages of sampling (BH, H and SM), respectively (p < 0.05). The positive effects of the bacteria application also extends for the stress indicators including: cortisol (0.175, 0.3 and 0.335 μM/ml), glucose (0.9, 1.25 and 0.6 μg/ml) and lactate (2.7, 3 and 3.35) μg/ml and plasma electrolytes consisting of Na+ (178.5, 175.43 and 175.8 mmol/l) and Cl−(123.85, 119.30 and 118.43 mmol/l) in all sampling stages (BH, H and SM), respectively (p < 0.05). Put it all together, P. acidilactici, acting as a probiotic, helps reducing stress symptoms in green terror fish.