Researchers have used phytochemicals as sustainable and valuable additives to improve reproduction traits and stimulate the immune system in farm-raised fish species followed by minimizing environmental and public health risks. In this regard, phytochemicals are plant-based bioactive compounds and are known as secondary metabolites. They contain various compounds with a remarkable potential to influence the reproductive performance of aquatic animals. Phytochemicals offer a promising approach to regulate reproductive performance and improve productivity in intensive aquaculture. According to the growing demand for eco-friendly solutions, phytochemicals reduce oxidative stress and enhance disease resistance in different farm-raised fish species. They have various bioactive compounds with unique physiological effects, especially on the reproductive performance of aquatic animals. However, the exact mode of action of these additives on aquatic reproduction traits is not yet well-documented. Overall, phytochemicals can be used as a practical alternative to synthetic additives and have the potential to promote sustainability in different aquaculture sectors around the world based on the availability and affordability of medicinal plants in the region. Polyphenols, flavonoids, isoflavones, anthocyanins, phytoestrogens, terpenoids, carotenoids, limonoids, phytosterols, and glucosinolates are well-known phytochemical molecules with innumerable properties in the host such as antibacterial, antiviral, antioxidant, and anti-inflammatory activities. These compounds are commonly administered orally in aquatic animals. Notably, plant extracts containing bioactive compounds like saponins and flavonoids play a vital role in inducing sexual inversion and fertility disorders. However, the concentration of phenolic compounds varies depending on the herbal genetics (genus, species, cultivar, and genotype), plant extraction methods, environmental conditions, and aquatic animal maturation status. Most studies declared that phytochemicals have a profound effect on fish reproduction due to their various bioactive compounds. They can also induce sexual maturation by interacting with hormone receptors, promote gonadal development by stimulating gonadotropin production, improve sperm quality through antioxidant properties, modulate hormone levels, and support reproductive behavior. However, the effects vary based on fish and plant species, dosage, and exposure duration. Further research is needed to optimize the use of phytochemicals in improving reproductive performance in farmed fish.