Growth Performance and Feed Utilization of African Catfish (Clarias gariepinus) Fingerlings Fed Diets with Graded Proportions of Selected Citrus Peel Additives

Abstract

An 8-week feeding trial was designed to assess the dietary influence of tangerine (TGR), tangelo (TGL), and orange (ORG) peels as dietary additives, on nutrient utilization and growth outcomes in African catfish (Clarias gariepinus) fingerlings. Seven isonitrogenous diets (40% crude protein) were compounded, each incorporating binary combinations of the citrus peels at a 75:25 inclusion ratio (ORG-TGR, TGR-ORG, ORG-TGL, TGL-ORG, TGR-TGL, TGL-TGR), alongside a control diet supplemented with 100% vitamin premix. A total of 210 fingerlings (mean initial weight: 4.51 ± 0.05 g/fish) were randomly allotted across 21 tanks (10 fish per tank) in triplicate and offered the respective diets twice daily for 56 days. Among all dietary treatments, fish fed the TGL-ORG blend demonstrated the most favourable growth response, achieving the greatest mean weight gain (2.66 ± 0.90 g), specific growth rate (0.82 ± 0.03% day⁻¹), and feed efficiency ratio, coupled with the lowest feed conversion ratio (1.17 ± 0.06). Statistically significant differences (p < 0.05) were observed among treatments for mean final weight, weight gain, and specific growth rate. Fish fed TGR-TGL combination recorded the highest survival rate, while the control group recorded the lowest. These findings demonstrate that the inclusion of citrus peel blends particularly TGL-ORG in catfish diets can substantially enhance both growth and nutrient utilization, offering a cost-effective, plant-derived alternative to conventional vitamin premix supplementation.