Partial Substitution of Fishmeal with Mopane Worm Meal in Dusky Kob Fingerling (Argyrosomus japonicus) Diets: Feed Utilization, Digestive Enzyme Activity, Blood Parameters, and Growth Performance

The use of protein-rich mopane worm meal (MPWM) in marine fish diets has the potential to reduce overall demand for fishmeal (FM) and thus promote economically ecologically sustainable dusky kob aquaculture. Therefore, this study investigated effect graded levels MPWM on feed nutrient utilization, digestive enzymes, blood parameters, growth performance fingerlings (Argyrosomus japonicus, Temminck Schlegel, 1843) over a 7-week feeding trial. Five isonitrogenous isoenergetic commercial were formulated by substituting 0 (MPWM0), 3 (MPWM3), 6 (MPWM6), 9 (MPWM9), 18% (MPWM18) FM with offered at 2.8% body weight. Two-thousand (average weight 15.68 ± 0.25 g) evenly distributed into 20 experimental tanks recirculating aquaculture system. Weight measurements taken weekly, while intestinal samples end experiment. inclusion quadratically influenced (y = 39.25 (±1.27) + 0.89 (±0.36)x − 0.04 (0.02) x2; R2 0.23; p 0.03) intake. Overall gain specific rate (SGR) linearly increased conversion ratio (FCR) declined levels. Substituting did not alter (p > 0.05) enzyme activities haematological parameters. Among serum biochemical components measured, only urea response levels, no trends observed other components. It was concluded that replacing 11.13% diet formulations does compromise intake, utilization efficiency, rate, physiological status juvenile kob.