Dietary supplementation of Terminalia arjuna bark extract improved growth, biochemical parameters and innate immunity in Heteropneustes fossilis larvae

Achieving healthy aquatic environment has been elusive with the process of intensification due to irrational use of chemicals. Plant extracts are hence candidate of choice as an alternative in aquaculture. Moreover, the poor larval survival of Heteropneustes fossilis (singhi) needs urgent research attention, which can be effectively addressed by boosting immunity, particularly by enhancing nonspecific immunity in the larvae. Hence, the study investigates the effects of dietary supplementation of Terminalia arjuna (TA) methanolic bark extract on growth, immune bio-markers and biochemical status in the stinging catfish, Heteropneustes fossilis larvae. 180 numbers of fish larvae (15 days post hatch; 22 +/- 2.6 mm mean length and 43 +/- 3.5 mg mean weight) were equally distributed in to four groups and fed with 0 % (control), 0.1 %, 0.25 % and 0.5 % of TA supplemented feed. Growth attributes, non-specific immune and biochemical parameters were analysed after 40 days of feeding. Results demonstrated that, larval group fed with 0.25 % TA extract had significantly (P < 0.05) improved final body weight, weight gain percent, daily weight gain and SGR compared to other treatment groups. Supplementation with 0.25 % TA extract significantly (P < 0.05) elevated respiratory burst activity (RBA), myeloperoxidase ac-tivity (MPO), lysozyme and biochemical parameters including alkaline phosphatase (ALP) ac-tivity, total protein, albumin as well as SOD level. However, 0.5 % TA dietary group revealed reduced growth and compromised immunity in the larva. Moreover, 0.25 % level significantly (P < 0.05) reduced hepato-cellular enzymes like ALT and AST activities and glucose as compared to control. However, the increase in extract level up to 0.5 % in the diet exhibited stress, which is evident from undermined growth and immunity. The present study suggests that the dietary TA bark extract inclusion level up to 0.25 % is safe limit and can modulate immunity, antioxidant and growth performance in stinging catfish, H. fossilis larvae.