Plant-based semen extenders in resource-limited aquaculture: A systematic review of cucumber juice for African catfish

Abstract

Conventional semen extenders pose challenges in resource-limited settings due to high costs and cold chain dependency. This systematic review evaluates plant-based alternatives, emphasizing cucumber juice (Cucumis sativus) for African catfish (Clarias gariepinus). Following PRISMA guidelines, searches of Scopus, PubMed, and Google Scholar identified 48 studies (35 mammalian, 13 non-mammalian) meeting inclusion criteria. Analysis reveals that plant-based extenders function through dual antioxidant and antimicrobial mechanisms: phytochemicals (phenolics, flavonoids, carotenoids, vitamins) scavenge reactive oxygen species while organic acids suppress bacterial proliferation below the spermicidal threshold of 10⁶-10⁷ CFU/mL. Optimal cucumber juice concentrations of 10-20% (v/v) improved motility duration, fertility, and hatchability in C. gariepinus while reducing oxidative markers and bacterial loads. A critical finding is the persistent divergence between mammalian cryopreservation-focused research and aquaculture's emphasis on ambient-temperature solutions using whole plant materials a translational gap representing both limitation and opportunity. Critical appraisal revealed methodological heterogeneity in extract preparation (fresh juices, aqueous/methanolic extracts, commercial lecithin) and inconsistent outcome reporting, with only 25% of studies including fertility outcomes and 43.8% reporting microbial data. No studies provided economic analyses despite claims of affordability. Research priorities include mechanistic characterization of bioactive compounds, standardized preparation protocols, fertility validation under field conditions, and cost-benefit analyses. This review confirms cucumber juice-based extenders offer a sustainable technology for artificial reproduction in resource-limited aquaculture, though standardized protocols and field validation remain essential prerequisites for widespread adoption.