An Evaluation of Iso-Nitrogenous Floating and Sinking Diets on Growth, Feed Utilization and Apparent Digestibility of the Redbreast Tilapia (Coptodon rendalli Boulenger, 1897)

One of the main challenges in the tilapia culture in Malawi is the low growth rates and yields. This study aimed to compare iso-nitrogenous fish feeds concerning growth, feed utilization, and apparent digestibility of the redbreast tilapia (Coptodon rendalli) raised in pond-hapas and tanks. Coptodon rendalli fingerlings were stocked in hapas (1m² each) at 10 fish per hapa, each measuring 6.81± 0.33g, and reared for 70 days. The fish were fed on floating, sinking, and maize bran (control) feeds. In a parallel digestibility experiment, six aquarium glass tanks were stocked with 10 Coptodon rendalli fingerlings, each for 21 days. Fecal material was collected and transferred into conical flasks after one hour of feeding for storage at -20°C. Results showed significant differences in specific growth rate, weight gain, relative condition factor, final weight, and survival rate, with floating feeds yielding the highest values (P< 0.001). The fish displayed negative allometric growth, with a growth coefficient of b=1.84. Apparent feed conversion ratio and protein efficiency ratio varied significantly across treatments (P< 0.001). In the digestibility experiment, differences in protein digestibility were also significant (P< 0.001), while no significant differences were observed in fat (P = 0.22), ash (P = 0.53), and energy (P = 0.34) across treatments. Fish fed on floating feeds exhibited better growth, feed utilization, and digestibility, highlighting the need to enhance the use of floating feeds in aquacultureBottom of Form