Growth, feed utilization and digestibility of <i>Oreochromis shiranus</i> (Boulenger 1905) fed dietary yellow mealworm larvae ( <i>Tenebrio molitor)</i> meal raised in earthen ponds

This study investigated the effects of incorporating yellow mealworm larvae (Tenebrio molitor) on the growth, feed utilization, and digestibility of Oreochromis shiranus, a dominant aquaculture species in Malawi. Four isonitrogenous diets were formulated by replacing fishmeal with yellow mealworms at 0%, 25%, 50%, and 75%. The formulated feed was fed to 720 fingerlings (15.05 ± 2 g) for 126 days in 12 experimental concrete ponds for the growth trial. A digestibility trial was conducted with 240 juveniles (49.63 ± 1.68g) fed for 40 days in 12 150 L tanks, followed by biochemical analysis. Results showed that replacing fishmeal with yellow mealworm had no significant effect on the final average body weight, weight gain, specific growth rate, feed intake, apparent feed conversion ratio, and survival rate of O. shiranus fingerlings. However, a significant difference in hepatosomatic indices was observed, though effect size was small. Apparent digestibility coefficients for dry matter, ash, and crude fat were higher for diets with yellow mealworm inclusion than diet with fishmeal only (p < 0.05). In contrast, the inclusion of yellow mealworm did not affect the digestibility of crude protein or gross energy. These findings suggest that yellow mealworm larvae can replace up to 75% of fishmeal without compromising growth and feed utilization of O. shiranus.