Utilization of Plant-based Nutraceuticals for Optimizing Fish Reproduction in Aquaculture

Plant-derived nutraceuticals are increasingly incorporated into aquafeeds as functional ingredients that may influence fish reproductive physiology, gamete quality, and spawning outcomes. Their effects span beneficial actions, such as antioxidant protection of gonads and gametes, immunoendocrine stabilization under farming stressors, and modulation of metabolic pathways supporting steroidogenesis and vitellogenesis, as well as potentially adverse endocrine-disrupting outcomes when estrogenic phytochemicals are present at inappropriate doses or life stages. This review synthesizes mechanistic understanding and experimental evidence on how botanical nutraceuticals—including polyphenols, phytoestrogens, carotenoids and pigment-rich matrices, essential oils, and algae- or leaf-derived bioactive complexes—interact with the hypothalamic–pituitary–gonadal axis, redox signaling, lipid metabolism, gut–microbiome processes, and epigenetic programming relevant to reproduction. Evidence from teleost models and aquaculture species indicates that outcomes are strongly context dependent, governed by ingredient standardization, bioavailability, species- and sex-specific sensitivity, reproductive stage, and environmental conditions such as salinity or pollutant exposure. Translational opportunities include broodstock diet design to improve sperm motility, egg biochemical quality, larval robustness, and reproductive resilience in variable culture environments, alongside cautionary strategies to avoid unintended feminization, disrupted sex differentiation, or compromised gametogenesis. Practical considerations for aquaculture implementation are discussed, emphasizing quality control, dose optimization, safety assessment, and research directions to strengthen causality and reproducibility.