Optimized co-feeding strategy of Anabas testudineus (Bloch 1792) larvae with enriched Moina micrura and egg custard-based inert diet; effects on growth, survival, and physio-metabolic responses

In this study, 7500 Anabas testudineus (climbing perch) larvae were fed different diets, including vitamin E-enriched Moina micrura and egg custard-based inert diet, to study their growth, survival and physio-metabolic responses over a 30-day rearing period. The study comprised two control groups: C1, which received 100% vitamin E-enriched Moina for 30 days, and C2, which received a 100% egg custard-based inert diet for 30 days. Additionally, three treatment groups were included, which were fed with varying levels of enriched Moina and egg custard in different ratios and for different durations through co-feeding regimens. The egg custard-based inert diet had 40.98% crude protein and 6.69% ether extract. The results of the present study indicated that final body weight, weight gain, and specific growth rate were significantly ( p ˂ 0.05) higher in T3 group, in which larvae fed with 75% enriched Moina + 25% egg custard for first 15 days, 50% enriched Moina + 50% egg custard for next 5 days, 25% enriched Moina + 75% egg custard for next 5 days; 0% enriched Moina + 100% egg custard for next 5 days. In addition, significantly ( p ˂ 0.05) higher survival was obtained in C1 followed by T3 group. The appropriate co-feeding strategy based on digestive enzyme activity was observed in T3 and T2 groups. In terms of glucose, cortisol, superoxide dismutase (SOD), and catalase (CAT) levels, no significant difference ( p ˃ 0.05) was observed between C1 and T3 groups. Moreover, significantly ( p ˂ 0.05) higher levels of glutathione peroxidase (GPx) activity were observed in C1 and T3 groups. The activity of metabolic enzymes was also significantly affected by the co-feeding strategy. Overall, the T3 group showed improved growth and enzyme activity compared to other treatments. Thus, the present study establishes a co-feeding strategy by using vitamin E-enriched M. micrura and egg custard-based inert diet at levels as followed for the T3 group to boost the growth performance and physio-metabolic activity in A. testudineus larvae.