Effects of Periplaneta americana powder instead of fishmeal on growth performance, antioxidant capacity and intestinal microbiota in Southern catfish (Silurus meridionalis)

American cockroach (Periplaneta americana) is rich in high protein and various active ingredients, and its powder is a high-quality source of protein. In present study, four isonitrogenous and isolipidic diets replacing 0 %, 10 %, 20 %, and 30 % fish meal with P. americana powder (PAP) were formulated for a 56-day feeding trial with southern catfish (Silurus meridionalis). Our findings revealed that 10 % PAP substitution significantly enhanced growth performance (WGR: 404.07 ± 22.02, p < 0.05), improved feed efficiency (FCR: 1.02 ± 0.003, p < 0.05), boosted antioxidant capacity (elevated SOD activity and reduced MDA levels, p < 0.05), and reduced liver injuries. However, higher substitution ratios impaired growth, antioxidant capacity, and caused tissue injuries in liver and intestine. 16S rDNA sequencing revealed that 10 % PAP increased intestinal abundance of anaerobic bacteria (Bacteroidaceae, Barnesiellaceae, Fusobacteriaceae, and Peptostreptococcaceae), which may be associated with adaptive responses to PAP utilization. These findings indicate that 10 % PAP optimally replaces fish meal in southern catfish diets, with anaerobic fermentation potentially playing a key role in PAP utilization.