Control of Reproduction in Oreochromis niloticus (Linnaeus 1758) Using Kola acuminata Seeds Powder as Reproduction Inhibitor

Abstract

Background and Objective: The use of synthetic chemicals in the production of food for human consumption has been condemned by many nations, due to their potential health and environmental hazards. The present study aimed to evaluate the impact of Kola acuminata (K. acuminata) seed powder on the reproductive performance of Nile tilapia (Oreochromis niloticus) through gonadal sterilization. Materials and Methods: Over 60-days at Ongot Fish Farm, 240 juveniles (average weight 16±5.5g) were randomly assigned to four experimental treatments, each with three replicates. The treatments included different dietary levels of K. acuminata seed powder: T1 (0% K. acuminata), T2 (10% K. acuminata), T3 (15% K. acuminata), and T4 (20% K. acuminata). A 35.5% iso-protein feed was formulated using an Excel spreadsheet, and the fish were housed in hapas within a 302 m² pond. Key parameters such as water quality, fish growth, reproductive metrics, and histopathological changes were monitored throughout the study. Results: Results showed that water quality remained within acceptable ranges throughout the study. The administration of K. acuminata seed powder did not significantly (p > 0.05) affect the fish's weight, weight gain, specific growth rate, survival rate, or condition factor. A negative correlation was found between ovary weight and individual fish weight (R = -0.87; p ≤ 0.05). Fish fed K. acuminata diets exhibited significant reductions in egg diameter, wet weight, and volume (p < 0.05). Moreover, the spawning percentage was lower in fish fed K. acuminata, and histological changes in the ovaries, such as vacuoles in the ooplasm and pyknotic nuclei in granulosa cells, were observed (p < 0.05). Conclusion: Dietary supplementation of K. acuminata seed powder affected the growth, reproductive performance, and ovarian histology of Nile tilapia, likely due to the presence of alkaloids and flavonoids. Based on the findings, it is recommended that farmers considering K. acuminata for breeding control limit its inclusion to a maximum of 20% K. acuminata powder per kg of feed.